Hand-held optically readable character set reader having automatic focus control for operation over a range of distances

ABSTRACT

An indicia reader operable over a broad range of distances and a method for reading indicia therewith. The indicia reader having a sensor and a distance determining device. The indicia reader being capable of configuring itself to read indicia at the determined distance. The indicia reader can have an aiming aid, communications capability, a keyboard, a motor, an actuator, an intensity sensor as well as audio and visual signaling components. The method of using involves the steps of determining distance and configuring the device to read. Other steps can include aiming, reading, decoding, automatic termination, communicating, signaling and automatic reinitiation.

CROSS REFERENCES

A. Related Applications

The present application is a continuation of application Ser. No.08/751,382, filed Nov. 19, 1996 (now U.S. Pat. No. 5,837,987, issuedNov. 17, 1998); which is a continuation of application Ser. No.08/309,334, filed Sep. 19, 1994 (now U.S. Pat. No. 5,576,529, issuedNov. 19, 1996); which is a continuation-in-part of application Ser. No.08/215,112, filed Mar. 17, 1994 (now U.S. Pat. No. 5,640,001, issuedJun. 17, 1997); which is a continuation-in-part of application Ser. No.07/947,036, filed Sep. 16, 1992 (now U.S. Pat. No. 5,308,966, issued May3, 1994); which is a continuation of application Ser. No. 07/875,791,filed Apr. 27, 1992 (now abandoned); which is a continuation-in-part ofapplication Ser. No. 07/422,052, filed Oct. 16, 1989 (now abandoned);which is a division of application Ser. No. 06/894,689, filed Oct. 8,1986 (now U.S. Pat. No. 4,877,949, issued Oct. 31, 1989).

B. Incorporations by Reference

The following related commonly owned patent applications areincorporated herein by reference:

    __________________________________________________________________________    Docket No.                                                                           Inventor(s)                                                                            Ser. No.                                                                             Filing Date                                                                          Patent No                                                                             Issue Date                              __________________________________________________________________________    5726   White    06/905,779                                                                           09/10/86                                                                             4,882,476                                                                             11/21/89                                6231   Miller, et al                                                                          07/136,097                                                                           12/21/87                                               5769X  Danielson, et al                                                                       07/143,921                                                                           01/14/88                                               6240   Koenck   07/238,701                                                                           08/31/88                                               6697   Main, et al                                                                            07/321,932                                                                           03/09/89                                               6767   Danielson, et al                                                                       07/364,902                                                                           06/08/89                                                                             WO/90/16033                                                                           12/27/90                                5854BB Chadima, et al                                                                         07/339,953                                                                           04/18/89                                                                             4,894,523                                                                             01/16/90                                35740X Danielson, et al                                                                       07/422,052                                                                           10/16/89                                                                             4,877,949                                                                             10/31/89                                6649XX Phillip Miller et al                                                                   07/347,602                                                                           05/03/89                                               36767YXX                                                                             Koenck   07/987,574                                                                           12/08/92                                               __________________________________________________________________________    The subject matter of certain of the above cases has been published as        follows:                                                                      Ser. No.       Related Publication                                                                           Publication Date                               __________________________________________________________________________    06/905,779     U.S. Pat. No. 4,882,476                                                                       11/21/89                                       07/364,902     WO 90/16033     12/27/90                                       07/422,052     U.S. Pat. No. 4,877,949                                                                       10/31/89                                       07/339,953     U.S. Pat. No. 4,894,523                                                                       01/16/90                                       __________________________________________________________________________    The entire disclosures of the foregoing publications are incorporated         herein in their entirety                                                      by reference. The following additional disclosures are also incorporated      herein in their                                                               entirety by reference:                                                        PCT International                                                                          International                                                                           International                                                                           International                                Application No                                                                             Filing Date                                                                             Publication No                                                                          Publication Date                             __________________________________________________________________________    PCT/US93/02139                                                                             10 March 1993                                                                           WO 93/18478                                                                             16 Sept. 1993                                PCT/US92/06157                                                                             23 July 1992                                                                            WO 93/14470                                                                             22 July 1993                                 PCT/US94/05380                                                                             11 May 1994                                                                             (Priority Date 11 May 1993)                            PCT/US93/12459                                                                             21 Dec. 1993                                                                            WO 94/15314                                                                             7 July 1994                                  __________________________________________________________________________

The following related applications are also incorporated herein in theirentirety by reference: Ser. No. 08/215,112, filed Mar. 17, 1994; Ser.No. 07/875,791, filed Apr. 27, 1992; Ser. No. 06/894,689, filed Aug. 8,1986; Ser. No. 07/965,983, filed Oct. 23, 1992; Ser. No. 07/719,731,filed Jun. 24, 1991; and Ser. No. 07/441,007.

AUTHORIZATION PURSUANT TO 37 CFR 1.71 (D) AND (E)

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND OF THE INVENTION

The present invention is particularly concerned with improvements ininstant optical character set readers of the type shown in U.S. Pat.Nos. 4,282,425 and 4,570,057. The disclosures of these United Statespatents are incorporated herein by reference by way of background.

The instant type of bar code reader with flashable illuminator means hasproved to be extremely desirable for portable applications because ofits unique simplicity and compact design. A significant goal of thepresent invention is to retain the major advantages of the presentcommercial instant readers with flashable illuminator means whileenhancing the capacity for reading optical information sets ofsubstantially greater dimesnion. An important related aspect of theinvention is to enable the reading of such information sets byilluminating the same with an instantaneous flash of light while theinformation sets are at a greater distance from the frontal end of thereader. A further development goal is to more effectively adapt thereading operation both to close up information sets of high reflectivityand to labels at greater distances and of curved configuration.

SUMMARY OF THE INVENTION

The present invention is therefore particularly directed to theprovision of an instant bar code reader which, while retaining theadvantages of simplicity, ease of hand operation and ruggedness,achieves enhanced versatility by its ability to read optical informationsets of greater length and multiple dimensions and to adapt to a greaterrange of reading distances. Such enhanced versatility is realized byproviding the reader with an automatically controlled lens system andoperating such control in accordance with a measure of reading distance.Further improvements are achieved by monitoring an average of reflectedlight from the bar code during a reading operation, and terminatingintegration of the reflected light from a bar code after an optimummeasurement sample of the reflected light image has been received.

Aiming of the reader may be carried out with the assistance of visiblemarker light beams directed into the field of view of the reflectedlight image sensor. In an ideal embodiment, the marker beams extend fromopposite ends of the information set image sensor through the reflectedlight optics so that the beams delineate the desired locations for theopposite ends of an information set in the reader field of view.

For the sake of energy conservation during portable operation, automaticcontrol of the lens system may be disabled until such time as theinformation set is within an effective reading range. Where a capacitordischarge energizes a flashable illuminator, the capacitor dischargecurrent may be interrupted as soon as an adequate amount of reflectedlight has been received; this not only reduces battery drain but alsospeeds up the capacitor recharging cycle: By monitoring the charge onthe capacitor, a new reading cycle can be initiated after a minimum timelapse, should an initial reading cycle be unsuccessful. Accordingly, itis an object of the invention to provide an information set readerconfiguration particularly suited to hand held operation whileexhibiting increased versatility.

A more specific object is to provide an information set reader capableof reading a wider range of information sets of varying types withoutsacrifice of essential simplicity and ease in hand held operation.

Another object is to provide an information set reader capable of rapidand efficient alignment with information sets located at substantialdistances from the reader.

A further object of the invention is to provide an instant informationset reader which achieves the foregoing objects while minimizing energyconsumption so as to retain a Capacity for extended portable operation.

A feature of the invention resides in the provision of an adaptive barcode image sensor system enabling a succession of readings of a giveninformation set with reflected light from respective different segmentsof such information set controlling respective integration times. Thisfeature is applicable, for example, to information sets on curvedsubstrates such that an information set reading with a singleintegration time would not effectively sample reflected light from allsegments of the label.

Further features leading to enhanced adaptability of the code imagesensor system comprise individually operable flash illumination meansenabling more rapid flash sequences, and/or enabling improvedillumination of irregular or curved code configurations and/or of codeconfigurations of greater extent, and/or enabling respectiveindividually controlled flash durations immediately following eachother, and e.g. adapted to respective different segments of a codeconfiguration.

Still further features of an adaptive code image sensor system relate tosimultaneous reading of code segments at markedly different depths offield and/or multiple depth measurement sensors for assessing the depthof respective segments of a code configuration, and/or selectable range,distance to image sensors effectively adapted to read codeconfigurations at respective overlapping ranges for instantaneousadaptation to a code configuration at any range, distance over a widerange without the use of moving parts. In one implementation, theeffective usable range of a lens system is greatly increased byproviding multiple optical image paths of respective different lengthsin the reader which lead through the lens system to respectiveindependently controllable image sensors.

Another feature resides in the provision of a marker beam indicatorsystem for delineating the optimum location for an information set inthe reader field of view so that the reader can be positioned rapidlyand efficiently even while at substantial distances from an opticallyreadable information set. Various method features will be apparent fromthe following disclosure. For example, in a case where a curved bar codelabel (or other optically readable information set) has a centralsegment within the focal depth of the lens system, but the marginalsegments are actually outside the focal depth, one exemplary method ofprogrammed operation may provide for a second flash automatically afterthe lens system has automatically focused at a selected greater depth.By assembling the two readings, e.g. pixel by pixel, a good reading maybe obtained with, e.g., valid start and stop characters being obtainedfrom the second reading.

In another method of programmed operation, a display forming part of theoperator input/output means can instruct the operator to take first areading of the left hand portion of a severely curved label, then acentral portion and then a right hand portion, with the processorassembling the pixels of the respective readings to obtain complete barcode image reading.

The operator could, in another mode, advise the reader processor, e.g.,by the selective actuation of function keys or the like, of a particularreading sequence to be input to the reader processor for extremely longor sharply curved labels. The function preys could be part of a keyboardassociated with the reader itself and/or a keyboard associated with ahost computer unit directly mechanically coupled with the readerhousing, or coupled via any suitable remote linkage means such as acable or a radio frequency channel. In certain instances, the readerprocessor may assemble the pixels of successive readings not only withthe assistance of internal check characters and preknowledge of codeformats and the like and/or of specific reading sequences, but furtherwith the assistance of measurements from multiple distance measurementsensors defining the general bar code spacial configuration. Utilizingmultiple flashable illuminators and/or multiple intensity sensors mayenable valid reading of different segments while avoiding in all cases,any saturation of CCD charge wells or the like of an image sensor.Saturation of any part of a CCD shift register may adversely affectsubsequent operation of an image sensor.

Other objects, features and advantages of the invention will be apparentfrom the following detailed description taken in conjunction with theaccompanying sheets of drawings, and from the features and relationshipsof the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a preferred embodiment of thepresent invention;

FIG. 2 is a diagrammatic view useful for explaining certain features ofa specific exemplary embodiment of the invention.

FIG. 3 is a somewhat diagrammatic partial longitudinal sectional viewfor indicating the application of certain features of the presentinvention to is an instant optically readable information readergenerally as shown in U.S. Pat. No. 4,570,057;

FIG. 4 is a somewhat diagrammatic plan view illustrating an adaptiveinformation set image sensor system in accordance with the presentinvention, and also illustrating an alternative information set guideindicator arrangement for the reader of FIG. 3;

FIGS. 5, 6 and 7 are electric circuit diagrams for illustrating anexemplary implementation of component 11 of FIG. 1;

FIGS. 6A through 6F show waveforms useful for explaining the operationof the circuit of FIG. 6;

FIGS. 8 and 9 show an exemplary implementation of components 15, 16 and17 FIG. 1;

FIG. 10 is an electric circuit diagram for illustrating an exemplaryimplementation for component 121 in FIG. 1;

FIGS. 11 and 12 are diagrammatic illustrations for indicating anexemplary implementation of component 20 in FIG. 1;

FIGS. 13 and 14 illustrate examples of alternative arrangements inaccordance with the invention;

FIG. 15 is a diagrammatic illustration of a laser bar code reader systemin accordance with the present invention;

FIG. 16 is a graphical illustration for explaining one embodiment offilter means for use in FIG. 15;

FIG. 17 illustrates another embodiment of filter means for use in FIG.15;

FIG. 18 is a diagrammatic end elevational view of a laser bar codescanner unit wherein the laser beam is to be swept over an extendedscanning path to read a relatively wide bar code label;

FIG. 19 is a somewhat diagrammatic view taken generally along the lineV--V of FIG. 18;

FIG. 20 is a diagrammatic view taken generally along the line VI--VI inFIG. 18 and indicating exemplary electronic circuitry for associationwith the swept laser beam scanner embodiment of FIGS. 18, 19 and 20;

FIG. 21 illustrates a wand type optically readable information setscanner in accordance with the present invention;

FIG. 22 is a longitudinal sectional view taken from the second figure ofU.S. Pat. No. 4,820,911 issued Apr. 11, 1989, and showing a modificationthereof so as to practice teachings in accordance with the presentinvention;

FIG. 23 is a longitudinal sectional view corresponding to FIG. 22, butindicating a duplication of parts as a mirror image with respect to ahorizontal plane so that teachings according to the present inventionmay be applied, and for example, the beam splitter of FIG. 22 omitted;

FIG. 24 shows an exemplary beam pattern at the reference plane for theembodiment of FIG. 23;

FIG. 25 shows a different exemplary beam pattern for FIG. 23;

FIG. 26 shows the relative spectral response of selenium and siliconphoto-voltaic materials, and inserts in the plot an exemplary lightsource output spectrum in the infrared region to which selenium andsilicon photocells would be differentially sensitive, e.g. without theuse of filters, and in addition to conventional narrow pass filterscentered at the laser diode wavelength;

FIG. 27 is a diagrammatic illustration of a stacked bar code which maybe read by the illustrated embodiments;

FIG. 28 is a diagrammatic partial rear elevational view showing ascanner with an external reflected light collector;

FIG. 29 is a somewhat diagrammatic partial longitudinal sectional viewof the scanner of FIG. 22, with a slip-on external photodetectorassembly applied to the frontal barrel portion of the scanner housing;

FIG. 30 is a somewhat diagrammatic horizontal sectional view of thestructure of

FIG. 29 for illustrating certain details of the external photodetectorassembly;

FIG. 31 is a diagram for illustrating the optical sensing area whichresults from the use of a typical solid state video imaging array and alens system with a magnification ratio of ten to one, in a hand-heldoptical reader as disclosed in U.S. Pat. No. 5,019,699 issued May 28,1991, and based on U.S. Ser. No. 07/238,701 which has been incorporatedherein by reference;

FIG. 32 is a diagrammatic illustration of a preferred form of hand-heldoptical reader as disclosed in the patent referenced in the precedingparagraph, and arranged so as to have its optical sensing areacompletely encompassing the machine-readable code (e.g. bar code) orhuman-readable information (e.g. line or lines of text) on a label sothat a complete instantaneous optical image thereof is converted by thereader into digital image data and stored in a processor memory of thereader;

FIGS. 33 and 34 correspond with the fourteenth and fifteen figures ofthe PCT international application published as WO 90/16033 on Dec. 27,1990 and which has been incorporated herein by reference;

FIG. 35 shows a scanner of the type shown in FIGS. 33 and 34 mounted ona vehicle by means of a universal mount of the type shown in theeighteenth figure of the incorporated application U.S. Ser. No.07/347,602, (such universal mount being per se covered by U.S. Pat. No.2,898,068);

FIG. 36 is a somewhat diagrammatic perspective view of an integratedhand-held bar code processing device capable of automatic scan and datadisplay and which may incorporate features shown in the second and thirdfigures of incorporated application U.S. Ser. No. 07/136,097;

FIG. 37 is a somewhat diagrammatic top plan view of the integratedscanner and terminal device of FIG. 36;

FIG. 38 illustrates a mechanical and electrical type of coupling whichmay be utilized for automatically coupling a scanner such as shown inFIGS. 33, 34, 35, or FIGS. 36, 37, with a universal mount such as shownin FIG. 21;

FIGS. 39 and 40 correspond with the first and twelfth figures ofincorporated U.S. Pat. No. 4,877,949;

FIG. 41 is a diagrammatic illustration of a laser diode deflected beambar code scanner such as may be employed in any of the scannerconfigurations disclosed herein including those of FIGS. 33-35 and36-37;

FIGS. 42A, 42B and 42C show electrical waveforms on a common time axisfor explaining an exemplary mode of operation of the laser scanner ofFIG. 41;

FIGS. 43A and 43B show electrical waveforms on a common time axis forillustrating operation of the laser scanner of FIG. 41 with modulatedpulses of light and a tuned detector/amplifier system;

FIG. 44 is a diagrammatic plan view showing the path of deflection ofthe laser beam for the scanner of FIG. 41, and showing a central angularrange of the laser beam path wherein the beam is to be used as aproximity sensor; and

FIG. 45 is a diagram for illustrating the optical sensing area as isdefined by a field of view of a lens system, such as from the use of atypical solid state video imaging array and a lens system with amagnification ratio of ten to one, in a hand-held optical reader inaccordance with the present invention;

FIG. 46 is a diagrammatic illustration of a preferred form of ahand-held optical reader according to the present invention, arranged soas to have its optical sensing area or field of view completelyencompassing the machine-readable code (e.g. bar code) or human-readableinformation (e.g. line or lines of text) on a label so that a completeinstantaneous optical image thereof is projected onto an area array ofphotosensors within the reader and may be converted by the reader intodigital image data and stored in a processor memory of the reader;

FIG. 47 is a block diagram illustrating a typical logic arrangement of amicroprocessor circuit and major functional components as are typicallyassociated with such a circuit, and further illustrating a preferredinterface between the array of photosensors of the reader as referred toin FIG. 46 and the microprocessor;

FIG. 48 is an illustration of a stacked bar code and of one of themanners in which a field of view of the optical reader is indicated to auser to facilitate alignment of the field of view with a label bearingindicia such as the stacked bar code;

FIG. 49 is an illustration of an alternate manner for indicating to auser of the optical reader the field of view of the informationgathering elements in accordance with the invention;

FIG. 50 is an illustration of yet another manner for indicating thefield of view of the optical reader;

FIG. 51 shows a schematically simplified view of a light source andrelated linear optics for delineating the field of view of the opticalreader as further described herein;

FIG. 52 is a diagrammatic illustration showing the reader of FIG. 46 andillustrating alternative embodiments relating to flashable light sourcesand aiming aids such as marker sources;

FIG. 53 shows another embodiment for delineating to a user of the readerits field of view, also showing a stacked bar code label encompassed ina vertical orientation within the delineated field of view;

FIG. 54 shows a variation of the embodiment of FIG. 53 for delineatingthe field of view of the reader, also showing a stacked bar code labelencompassed in a horizontal orientation within the delineated field ofview;

FIG. 55 is a diagrammatic illustration of a multiple optical paths forreading optical information sets over a substantial range of distances;and

FIG. 56 is a schematic of an exemplary circuit for monitoring andcontrolling exposure.

DETAILED DESCRIPTION

I. Description of FIGS. 1-14

FIG. 1 illustrates a preferred instant bar code reader system forextending the versatility of a commercial bar code reader such as shownin U.S. Pat. No. 4,570,057. Component 10, FIG. 1, may represent acontrol and processing means for the system and may include a centralprocessing unit, memory units and analog to digital conversion channels.

The central processing unit and associated memory form the main controlportion of the system. The other functional blocks of FIG. 1 may beinputs or outputs with respect to the central processing unit. Thecentral processing unit may be a microprocessor that executes theprogram to control the operation of the reader. The microprocessor actsas a microcontroller with the capability of sensing and controlling thefunctional elements of the bar code reader, and decoding the bar code assupplied from a bar code image sensor means 11. Where the reader iscoupled on line with a host computer system, (for example by a hostconnection means in the form of a flexible cable), the decoded barsignal is transmitted to the host under the control of the centralprocessing unit. The microprocessor is capable of static operation withshut-down for power conservation. Wake-up of the processor will occurwhen an operator actuates a scan switch 12.

An electrically erasable read only memory of component 10 may beutilized to store parameters and special modifiable decoding sequencesfor the bar code reader operation. Examples of these parameters would belabel code, and input/output speed and control format. Component 10 mayalso include a random access memory for data collection, decoding workspace and buffer storage of the decoded label data for transmission to ahost computer, for example. The random access memory can be internal tothe microprocessor chip or reside on a data bus. The analog/digitalchannels are for receiving the bar code signals generated by the barcode image sensor means 11 and for other purposes as will be hereafterexplained.

The image sensor means may, for example, include a photosensor arrayindicated diagrammatically at 13 having a one dimensional linear arrayof photodiodes for detecting the bar code reflection image. To readlabels with bar code lengths of greater than seven inches with highresolution requires that the array have relatively high resolution. Byway of example, the array 13 may comprise five thousand photodiodecircuits (5,000 pixels) and provide approximately three photodiodecircuits (3 pixels) for each five mils (0.005 inch) of a bar codelength. (Each pixel of array 13 may have a length of about sevenmicrons.) A charge coupled device (CCD) shift register may be arrangedto receive bar code signal elements from the respective photodiodecircuits after a suitable integration interval. Once the bar code signalelements have been transferred to the shift register, the signalelements are retained independently of further exposure of thephotodiodes to reflected light from the bar code.

In the embodiment of FIG. 1, an intensity sensor 14 is provided and maycomprise a photodiode that will determine the relative amount of lightexposure of the photosensor array 13. if component 10 operates atsufficiently high speed, the signal from the intensity sensor 14 may besupplied exclusively to component 10 via an analog/digital channel sothat the control and processing means can determine the optimum pointfor transfer of the bar code image signals to the shift register.Likewise, many CCD's now have an electronic shutter. In the foregoingexample the sensor 14 could drive a circuit to condition the input anddrive the CCD shutter pin (simple non-processor controlled exposurecontrol). The shutter control line stops the photo-discharge of theinternal CCD capacitors. This may be achieved electronically. Furtherexposure during the cycle results in no further charge reductions (see,for example, FIG. 56).

In a presently preferred implementation, however, the intensity sensormeans 14 is directly coupled with the hardware control circuits of theflashable illuminator means and of the bar code image sensor means, andthis is indicated by dash lines L1 and L2 in FIG. 1; in this case, lineL is used only so that the processor component 10 is advised that aflash has actually occurred. In a preferred embodiment wherein aflashable illuminator 15 is driven by capacitor discharge current, acomponent 16 may effect interruption of the flow of current from thecapacitor based directly on the signal supplied via L1 from intensitysensor 14. In this way, energy is conserved, and recharging of thecapacitor speeded up. Component 16 may comprise a flash currentinterrupter switch means, e.g., a solid state switch which is controlledto interrupt discharge of the capacitor of high voltage generation unit17, and thus, to terminate the flash of light from the flashableilluminator 15 when intensity sensor 14 indicates that adequatereflected light has been received from a bar code.

The system of FIG. 1 is also indicated as including a reading distanceadaptation means 20, label guide indicator means 21 and reading distancesensor means 22. These components are best understood by reference to aspecific example as shown in FIG. 2. FIG. 2 illustrates an exemplaryconfiguration wherein the label guide indicator means 21 (FIG. 1) isprovided by a pair of marker light emitting diodes 24 and 25 whichproduce light beams 26 and 27 extending from opposite ends of thephotosensor array 13 through the lens system indicated at 30 so as todelineate by means of marker light spots at 28 and 29 on the label thefield of view of the reader. FIG. 2 illustrates a situation where label31 has a bar code with a length greater than seven inches and is locatedat a distance D from a frontal window part 33 of the reader of greaterthan two inches, for example, three inches. By way of example in FIG. 2,flashable illuminator 15 of FIG. 1 is illustrated as being implementedby two flash tubes 35 and 36 directed obliquely outwardly relative to acentral axis 37 of the reader. FIG. 2 also illustrates the provision ofan ultrasonic transducer 38 for implementing component 22 of FIG. 1. Forexample, transducer 38 may emit an ultrasonic pulse along an axis 39aligned with the reader central plane such that the time of arrival of areflected pulse from the bar code label 31 provides a measure of readingdistance. In place of or in addition to distance sensor 38, infrareddistance measurement sensors 38-1 and 38-2 are provided in FIG. 2, withaxes arranged to intersect a curved label generally at a mean distance(e.g. at D₀ equal to one-half the sum of the maximum distance D₁ and theminimum distance D₁). By way of example, adaptation means 20 may includemotor driven focus adjustment means 40 coupled with the lens system 30for adjusting the lens system parallel to the central optical axis 37,as represented by the double-headed arrow 41. In the example of U.S.Pat. No. 4,570,057, the reader has a width dimension at its frontal wallwhich is greater than the extent of the exit light path at the plane ofsuch frontal wall. However, in the specific configuration of FIG. 2, itwill be observed that marginal light rays 43 and 44 from the flash tubes35 and 36 are transmitted by transparent side walls 45 and 46 of thereader housing so that in this case the illumination field has a totalextent at the plane of the reader frontal wall which is substantiallygreater than the width dimension of such frontal wall.

In FIG. 2, a photodiode intensity sensor 50 corresponding to component14 of FIG. 1 is indicated as being mounted centrally as defined by aplane intersecting the optical axis 37, but offset from photosensorarray 13 so as not to obstruct light incident thereon. (Optical axis 37intersects photodiode array 13.) Intensity sensor 50 is preferablyplaced so as to intercept light of maximum intensity as reflected fromthe label 31. By way of Example, intensity sensors such as 50, 51 and 52may be located at respective different locations adjacent sensor array13 as indicated, and successive ones of the sensors may tie selected foractual control of bar code image integration time during successive barcode reading operations for a given curved bar code configuration aswill be hereafter explained.

In the example of FIG. 2, mirror elements 53 and 54 are mounted atopposite ends of photosensor array 13 for reflecting light from thesources 24 and 25 along the beam paths 26 and 27. Components such as 11,14, 15, 20, 21 and 22 of FIG. 1 may be implemented as shown in FIG. 3.FIG. 3 may be taken as supplementing FIG. 2, and corresponding referencenumerals have been used in FIGS. 2 and 3 to designate similar parts.

Referring to the physical arrangement of parts as indicated in FIG. 3,the location of the intensity sensors such as 51 to one side of acentral optical axis 60 is indicated. Considering the plane whichintersects the photosensor array 13 and coincides with the optical axis;60, it will be understood that mirrors such as 53 will each have alocation centered on such plane. As indicated in FIG. 3, ultrasonictransducer 38 (FIG. 3) may be located just above window 33 with its axis39 directed generally parallel to the optical axis 64 (which indicatesthe axis for the reflected light entering the reader).

In conformity with FIG. 2, the reader is shown as having transparentside wall portions such as 46 at the respective sides of the reader,corresponding to the transparent portions 45 and 46 in FIG. 2. Each ofthe flash lamp tubes 35 and 36 array be provided with a housing 75 andan interior reflector 76 with a configuration as described as U.S. Pat.No. 4,570,057. At a depth of approximately three inches in front o-f thewindow 33, the flash illumination means 35 and 36 may effectivelyilluminate a sensing region having an extent greater than seven inches,for example.

Reflected light from a bar code label 31 follows an optical path asindicated at 64, 80, 81 and 60 in FIG. 3 by virtue of the arrangement ofmirrors 82, 83 and 84. These mirrors are fixed relative to readerhousing 86, while a lens barrel 90 carrying optical lenses is axiallyadjustable relative to the reader housing. Also preferably forming partof the adjustable lens barrel assembly 90 are an infrared rejectingfilter 97 and a rectangular aperture element analogous to that of U.S.Pat. No. 4,570,057. For the sake of diagrammatic indication, barrelassembly 90 is shown as having a series of gear teeth (rack) 101 meshingwith a worm gear drive 102 which is driven from an adjustment motor 103via a right angle drive coupling assembly 105. The barrel assembly 90may have a range of adjustment so as to accommodate bar code labelsclosely adjacent to the frontal window 33 and at progressively greaterdistances in front of the window 33 up to reading distances of at leastthree inches.

In FIG. 3, a bearing for the shaft of worm gear 102 is indicated at 111.Guide means for lens barrel 90 are indicated as comprising flanges suchas 112 for riding in cooperating slot-like low friction guideways suchas 114. An alternative location for the light emitting diodes 24 and 25is indicated at 24-1 in FIG. 3. An analog to digital conversion channelof component 10, FIG. 1 maybe utilized to monitor charge build-up in thehigh voltage generation component 17 so that a flash of the illuminatormeans 15 will take place only when the desired amount of flash drivingcurrent is available.

Other analog to digital conversion channels may read the light intensityvalues accumulated by intensity sensors 50, 51 and 52, so that suchintensity values can determine respective bar code image integrationtimes, where desired.

Component 120 in FIG. 1 represents audio and visual status indicatorsfor facilitating operation of the reader unit. For example, ared-light-emitting diode indicator may be energized whenever a thumbactuator controlling read enable switch 12 is pressed and the readingdistance sensor means determines that a bar code label is beyond themaximum reading distance of the reading distance adaptation means 20. Atsuch a distance outside of the operative reading range, the lensadjustment motor 103, FIG. 3, follows an optical path as indicated at64, 80, 81 and 60 in FIG. 3 by virtue of the arrangement of mirrors 82,83 and 84. These mirrors are fixed relative to reader housing 86, whilea lens barrel 90 carrying optical lenses is axially adjustable relativeto the reader housing. Also preferably forming part of the adjustablelens barrel assembly 90 are an infrared rejecting filter 97 and arectangular aperture element analogous to that of U.S. Pat. No.4,570,057. For the sake of diagrammatic indication, barrel assembly 90is shown as having a series of gear teeth 101 meshing with a worm (geardrive 102 which is driven from an adjustment motor 103 via a right angledrive coupling assembly 105. The barrel assembly 90 may have a range ofadjustment so as to accommodate bar code labels closely adjacent to thefrontal window 33 and at progressively greater distances in front of thewindow 33 up to reading distances of at least three inches. In FIG. 3, abearing for the shaft of worm gear 102 is indicated at 111. Guide meansfor lens barrel 90 are indicated as comprising flanges such as 112 forriding in cooperating slot-like low friction guideways such as 114.

An alternative location for the light emitting diodes 24 and 25 isindicated at 24-1 in FIG. 3. An analog to digital conversion channel ofcomponent 10, FIG. 1, may be utilized to monitor charge build-up in thehigh voltage generation component 17 so that a flash of the illuminatormeans 15 will take place only when the desired amount of charge isavailable. Other analog to digital conversion channels may read thelight intensity values accumulated by intensity sensors 50, 51 and 52,so that such intensity values can determine respective bar code imageintegration times, where desired.

Component 120 in FIG. 1 represents audio and visual status indicatorsfor facilitating operation of the reader unit. For example, ared-light-emitting diode indicator may be energized whenever a thumbactuator controlling read enable switch 12 is pressed and the readingdistance sensor means determines that a bar code label is beyond themaximum reading distance of the reading distance adaptation means 20. Atsuch a distance outside of the operative reading range, the lensadjustment motor 103, FIG. 3, may be disabled, e.g., by the programmingof control and processing means to conserve power. When the reader iswithin the operative range, if the thumb operated switch 12 is actuated,motor 103 is essentially continuously controlled according to successivedistance readings. If a good bar code reading is accomplished, means 120may produce a relatively long single beep and turn on a green lightemitting indicator diode. Where a bad bar code reading situation isdetermined, e.g., after a selected number of reading attempts, means 120may generate three short beeps, for example. The programming may be suchthat once a good reading or bad reading condition is determined, theuser must release the thumb switch and depress it again to initiateanother read sequence. Indicator lamps and a beeper have been shown inthe seventh figure of U.S. Pat. No. 4,570,057 and are described thereinat column 11, lines 37-43. The indicator lights may be physicallylocated forwardly of the thumb switch as can be seen in the first figureof U.S. Pat. No. 4,570,057.

FIG. 1 also indicates an input/output buffer component 121 for couplingthe control and processing means 10 with a host processor or the like. Aconnection means 122 may directly receive a host processor so that thehost processor housing is physically attached with the reader housing.As another example, connection means 122 may comprise a cable containingsix conductors. Preferably, such a cable would be detachable at thereader. In this second example, all needed voltages may be generated inthe reader from plus five volts supplied by two of the six conductors(+5V, GND). The other four signal lines of the cable are preferablyindependently programmable as inputs or outputs. By way of example, thehost processor may be part of a portable hand held computer such asshown in U.S. Pat. No. 4,455,523 and U.S. Pat. No. 4,553,081. Therechargeable batteries of the portable computer may supply all neededpower to the reader unit of the present invention. In the secondexample, a host computer unit can be carried in a belt holster forexample during extended use of the reader unit of the present invention.

FIG. 4 is a somewhat diagrammatic top plan view of an exemplary bar codeimage sensor means 11 such as indicated only schematically in FIG. 1. InFIG. 4, the sensor housing 124 is shown as having a light transparentcover window 125 overlying the photodiode array 13. Where the photodiodearray comprises five thousand individual elements or pixels, each with adimension of about seven microns, the intensity sensors 50, 51 and 52may each have a length of about one-tenth inch or more so as to spanmany bars of a reflected bar code image, e.g., at least six bar codeelements, and reliably sense an average intensity value which isessentially independent of any specific bar code sequence. By way ofexample, the intensity sensors may be cemented to the exterior surfaceof window 125 at successive locations along photodiode array 13 butoffset from the light entrance path to the photodiode array.

Mirrors 53 and 54, FIG. 2, may be cemented in place on the glass 125 asindicated for mirrors 53' and 54' in FIG. 4. The light sources 24' and25' in FIG. 4 may be located wall 130, FIG. 3, at a section as indicated241 in FIG. 3. The mirrors 53' and 54' are secured at angles such thatthe marker beams will extend parallel to the image path at E60, 81, 80and 64 and will produce spots of visible light, e.g., of red color,corresponding to spots 28 and 29 in FIG. 2, and spot 28 as indicated inFIG. 3.

In a preferred mode of operation of the embodiments of FIGS. 1-4, manualactuation of the read enable switch 12 will initiate a flash of theilluminator means 15 provided the reader is within its operative rangefrom a bar code label. If the reader i3 outside of such operative range,momentary actuation of the read enable switch 12 will activate a pair ofmarker beams such as 26, 27, FIG. 2 representing the lateral margins ofthe reader field of view. Then, if the reader is moved into operativerange is and the read enable switch 12 again actuated, the illuminatormeans 15 will be flashed regardless of the state of focus of theautomatically adjustable lens means 30, FIG. 2.

If the initial reading is found to be invalid, the marker beams willautomatically be turned on briefly to again delineate the reader fieldof view, and quickly thereafter the illuminator means will be flashedagain. This sequence can be repeated automatically (if the read enablebutton is held depressed), until the lens means 30 has beenautomatically adjusted for the distance of the bar code from the readerand E valid reading is obtained.

In the reading of a highly curved bar code label, a plurality ofreflected light intensity sensors such as 50, 51 and 52, FIG. 4, may besuccessively activated in successive flashes of the illuminator means15, the intensity sensors automatically controlling successiveintegration times of the bar code image sensor I 1, according to theaverage intensity of reflected light from respective different segmentsof the curved bar code. Respective segments of a curved bar code label131 have been indicated at 150, 151 and 152 in FIG. 2. In a first flashillumination of label 131, intensity sensor 51 might measure thereflected light from a bar code segment 151 on the label and causetransfer of the bar code image signals to a receiving means such as aCCD shift register after an integration time optimum for the reading ofbar code segment 151. In a second flash quickly following the first, theintensity sensor might control integration time so as to be optimum forthe bar code segment 152. Then in a third flash illumination of the barcode 131, the central intensity sensor 50 could control integrationtime. The control and processing means 10 would then assemble readingsfor bar code segments 151, 152 and 150 from the successive flashes ofilluminator means 15 to determine if a valid total reading had beenobtained. If not, a further succession of three flashes of theilluminator means could be enabled, with the indicator beams 28, 29being turned on in the interval while proper high voltage was buildingup for the further series of flashes. (Three capacitors of component 17,FIG. 1, could store charge and be discharged rapidly in succession toproduce three flashes in rapid sequence without any delay for capacitorrecharging.)

For the case of a highly curved bar code label such as indicated at131-1 in FIG. 2, distance sensors 38-1 and 38-2 might indicate that themargins of the bar code would be out of focus. In such a case, aspreviously mentioned in the introduction to the specification, theprocessor 10 could be programmed to flash both tubes 35 and 36 with theadjustment means 40 controlled according to the distance reading D2 assensed by the distance measurement means 38. Thereafter, control of theadjustment means 40 would be related to a distance such as indicated atD22 in FIG. 2 so that marginal portions of the label 131-1 would then bein focus. With the new focus automatically established, tubes 35 and 36could be again activated so as to read the marginal portions of the barcode on label 131-1, whereupon the processor component 10 could assemblethe two readings pixel by pixel to establish a complete bar code.

In another example as previously mentioned, the reader could be providedwith a display, and the processor component 10 could cause the displayto instruct the operator that the label 131-1 was to be read in twosegments, the reader first being positioned so as to be directed towardthe left portion of the label 131-1, e.g., with only a tube 36 flashed,and then in a second operation, the reader being physically adjusted soas to be directed toward the right hand portion of label 131-1, and, forexample, only the tube 35 flashed.

In another mode of operation as previously mentioned, the reader couldbe provided with a keyboard, and the operator noting the highly curvedconfiguration of label 131-1, could advise the processor component 10that a first reading would be taken of the left-hand portion of label131-1, after which a separate reading would be taken from the right-handportion of label 131-1.

Along with the multiple readings of a highly curved label such as 131-1,the processor 10 could also take account of distance measurements fromcomponents 38, 38-1 and 38-2, in assembling e.g., pixel by pixel, acomplete bar code from the successive readings.

A. Summary of Exemplary Operation for FIGS. 1 through 4

Since operation is determined by the programming of component 10, manydifferent modes of operation can be implemented. Generally, however, thereading distance sensor means 22 will be activated to read the distancebetween the front window 33 of the reader and one or more regions of abar code label. If the distance measured, such as D, FIG. 2, is greaterthan an operative range of the adaptation means 20, for example, greaterthan three inches, the adaptation means 20 may be disabled. Thus, forthe case of adjustable lens means 30, the motor driven focus adjustmentmeans 40 would be inactive as long as the distance sensor means such as38 determined that the distance D was outside of the operative range ofthe lens means 30. In this case, however, preferably the label guideindicator means 21 would be active as long as the scan switch 12 wasactuated by the operator, to produce the marker spots as indicated at 28and 29 in FIG. 2 and as indicated at 28 in FIG. 3. The marker beams 26and 27 would remain on while switch 12 was actuated and for an intervalof, for example, five seconds after release of switch 12, where thereading distance remained outside of the operative range.

Where the switch 12 is actuated and the reading distance sensor meansdetermines that the reading distance is within the operative range,component 10 checks the high voltage generation means 17 to determine ifproper voltage is present on the flash capacitor means and if so, turnsoff the label guide indicator means 21, FIG. 1, and effects a cleaningcycle of the bar code image sensor means 11 so as to prepare thephotosensor array 13 for a reading operation. The processor component 10then initiates a capacitor discharge to activate the flashableillumination means 15. In one embodiment, a single capacitor may bearranged to drive both of the flash tubes 35 and 36 of FIG. 2. Inanother embodiment, respective individual capacitors may be arranged todrive the respective tubes 35 and 36. In one mode, both capacitors maybe discharged to drive both of the tubes 35 and 36 simultaneously. Inthis mode, an intensity sensor 50, FIGS. 2 and 4, may control theduration of the integration time interval during which the reflected barcode image signal is accumulated at the sensor means 11. At the end ofthe integration interval, the bar code image signals are transferred forexample to a CCD shift register for readout from the sensor means 11.During the readout operation, the signals received by the shift registerare not affected by further light impinging on the photodiode array 13.Furthermore, at the end of the integration interval, the flash currentinterrupter switch 16 may be actuated so as to interrupt discharge fromthe relevant capacitor or capacitors. In this way, energy is conserved,and recharging of the capacitor means is sped up.

In a second mode of operation, a capacitor associated with flash tubemay be activated during a first reading interval under the control of anintensity sensor 51 for insuring an optimum reading of a bar codesegment such as indicated at 151 of a label 131, for example, of markedcurvature. In a second reading interval, the capacitor associated withflash tube 36 may be activated to illuminate particularly a bar codesegment 152, with the integration time of the bar code image sensormeans being under the control of an intensity sensor 52 arranged toreceive reflected light particularly from bar code segment 152. In oneexample, intensity sensor 5 1 would be arranged to generate an averagelight value by averaging reflected light emanating from a portion 191 ofsegment 151. Similarly, intensity sensor 52 would receive light from aportion such as 192 of segment 152 where reflected light intensity wouldbe greatest on the average. In this example, the programming ofcomponent 10 would be such as to generate the bar code from twosuccessive flashes, one of tube 35 and the other of tube 36. Where thebar code generated based on two such reading intervals fails to providea valid consistent reading for central segment 130, component 10 couldbe programmed to produce in a third reading interval, the simultaneousdischarge of both capacitors to simultaneously activate both of theflash tubes 35 and 36 under the control of the central intensity sensor50 which sensor 50 would receive light from a portion 190 of segment 150which would be expected to provide maximum average light intensity. Thecomponent could then be programmed to assemble a complete bar codereading from the three successive reading intervals.

The third interval might be driven by means of a third capacitorconnectable to both tubes 35 and 36 so that the three reading intervalscould be executed in quick succession. Where a first reading operationis unsuccessful for example, because of an incorrect position of theadjustable lens means 30, component 10 may be programmed to immediatelyturn on the label guide indicator means 21 during the interval when thecapacitor means is being automatically recharged for a succeeding secondreading operation. During the recharging operation, e.g., for a timeinterval of about ninety milliseconds, the label guide indicator means21 will remain on, and the reading distance sensor means 22 willrepeatedly measure the distance to the bar code label with anessentially continuous corresponding control of the lens means by thefocus adjustment means 40. As soon as the component 10 determines thateach of the capacitor means has attained the desired voltage for afurther flash illumination, thee image sensor means 11 will be againcleared and a new reading operation automatically carried out. In eachreading sequence as before, one or more of the intensity sensors 50, 51and 52 determines the time point at which the image signal or thephotodiode charge cells is transferred to the CCD shift register stages.Also, alter the appropriate integration interval or intervals, thecurrent interrupter switch 16 for a respective capacitor dischargecircuit is operated to terminate the capacitor discharge and extinguishthe flash of a respective illuminator means. The data resulting fromeach integration interval is transferred out of the image sensor means11 via the CCD shift register for processing in component 10. When asuccessful reading is determined by component 10, the correspondingindicator of component 12 will be activated, and for example, it will benecessary to release switch 12 before a further reading operation can beinitiated. Where a given reading operation is unsuccessful, theprogramming of component 10 may be such that the reading operation isautomatically repeated up to for example, ten times. Should tensuccessive reading attempts be unsuccessful, component 10 would producethe corresponding bad read condition indication via component 120, andagain, for example, it might be necessary for the operator to releaseswitch 12 before 15a further read sequence could be initiated. By way ofexample, once a valid bar code reading was obtained, the programmingcould be such that component 10 could establish communication with ahost computer system, for example, an accompanying portable computer, oran integral host computer. Where no further actuation of the switch 12occurs after a valid reading, the system may be programmed toautomatically power down so that a battery means, for example, withinreader housing 86, would be subject to the minimum drain during inactiveintervals of the reader system.

The foregoing modes of operation could be selected, for example, fromthe keyboard of a hand-held computer carried by the operator along withthe reader unit. The various optional modes of operation could becorrespondingly selected with all modes preprogrammed into thecomponent, or desired respective modes of operation could be obtained byloading the corresponding programming from the hand-held computer intocomponent, as desired. Other special modes of operation can beaccommodated such as machine gun scanning (which might be used inreading lists of labels). In such an operation, switch 12 could be helddepressed while the reader was moved over a series of labels, and theprogramming would be such as to discard identical adjacent bar codereadings. Also, changes could be effected in the operation of the goodand bad read indicators of component 120 and changes could be made inthe allowed number of retries and the like. While the foregoingdescription will enable those of ordinary skill in the art to understandand practice the present invention, the following supplementaldescription is given particularly for demonstrating the availability ofa suitable implementation utilizing low cost presently availablestandard commercial components.

B. Supplementary Discussion

As an example of implementation of the system of FIG. 1, component 10may be implemented as a Motorola MC68HCII microcontroller. Otherprocessor components which are presently commercially available includea NEC uPD783 10, a National HPC 1 6140, an Intel CMOS MCS8097, and aHitachi HD64180. Some such components would need more external devicesthan others, e.g., such as analog to digital conversion channels, ROM,RAM, EEPROM (or equivalent non-volatile RAM), etc. Generally, as higherspeed processors become available, and processors with more internalmemory and conversion facilities, the utilization of such processorswill be advantageous. FIGS. 5, 10, 11 and 12 herein are shown as usingsignals from the Motorola MC68HCI 1. All other inputs and outputs aregeneral processor pins, so that a drawing showing the processor ofcomponent 10 is not necessary.

In FIG. 5, reference numeral 11-1 indicates a specific component for usein the bar code image sensor means 11 of FIG. 1. By way of specificexample, component 11-1 may comprise a solid state integrated circuitchip such as type TCD106C image sensor or the equivalent. Component 11-1includes a charge coupled device (CCD) shift register driven for exampleutilizing two megahertz clock signals from driver components 201, 202and 203. Where components 201-203 are implemented as type 75361 drivers.These components serve to convert the five volt input logic signals tothe twelve volt level needed to drive component 11-1. Current sources205 and 206 in conjunction with resistors 207 and 208 provide a DCoffset to bring the video output levels from the shift registers into anacceptable input range for the analog to digital converter channels A/D3and A/D4 of component 10.

The microcontroller of component 10 could drive each signal linedirectly, but the bit manipulation capabilities of most presentlyavailable processors would provide a very slow preparation and readingcycle time for the case of a bar code image sensor size of 5000 pixels.The circuit shown in FIG. 5 uses an eight megahertz clock 220, FIG. 6,to produce a controlling sequence which can clock out two pixels everymicrosecond from component. The circuit of FIG. 6 allows continuousoperation such as is needed to (quickly prepare the component 11-1 for areading operation and also allows single-stepping operation to give theanalog to digital converter channels sufficient time to input eachpixel. The circuit of FIG. 6 allows each shift pulse to be synchronizedwith the clock rate at line 215, FIG. 5, (the 0110 clock line) forproper operation it is desirable to operate at the highest frequencypossible without unduly complicating or increasing the size of thedriver circuitry, Thus, an image sensor with a higher maximum clockingrate could be selected. In FIG. 6, reference characters 6A through 6Fhave been applied to various lines and the corresponding relatedwaveforms have been indicated in FIGS. 6A through 6F, respectively, byway of explanation of the operation of FIG. 6.

The outputs of FIG. 6 form respective inputs to drivers 201, 203 of FIG.5 as indicated by the respective designations of the corresponding linesin these figures. In FIG. 6A, reference numeral 231 indicates the firstpositive transition of the clock waveform after the signal (supplied bythe aforementioned MC68HC I I microcontroller) goes low, or the signalline SCYC goes high. In FIG. 6F, the signal SH follows the dash line 232if the signal SHEN is true. As indicated at 241-244 by dash lines, thecycling continues if the signal IVT remains low.

Component 11-1 requires twelve volts for proper operation and a circuitfor providing this voltage from the five volt supply available isindicated in FIG. 7. This circuit should be able to be powered down whennot in use in order to conserve power. A drawback of the circuit of FIG.7 is that when it is turned off, the inductor L1 provides plus fivevolts to the plus twelve volt circuits unless a transistor Q4 is addedto block the five volts.

Line 251 in FIG. 7 receives a switched plus five volts for supply to thedrivers 201-203 of FIG. 5. Line 251 may also supply five volts to anyother circuit which is not needed when the twelve volts is off. The fivevolts at line 251 is switched off with the plus twelve volts at line 252to completely power down the image sensor component 11-1 of FIG. 5 anddrivers 201-203. An output line 253 in FIG. 7 provides five volts whenthe twelve volts are shut off and provides twelve volts when the line254 (+(+12ENB)) is enabled.

The voltage at line 253 is used to drive an oscillator 255 of FIG. 8which is utilized in the present commercial instant bar code reader.Circuits suitable for implementing FIG. 7 desirably exhibit low cost,high efficiency and least number of parts.

FIG. 8 illustrates a suitable high voltage generator circuit forgenerating approximately 300 volts for the xenon flash tube 260illustrated in FIG. 9. The circuit shown in FIG. 8 is similar to that ofthe present commercial instant bar code reader. The transformer TI ofFIG. 8 uses a gapped core and is actually a transforming inductor.Magnetic energy is stored in the core on respective first half cycles,and on opposite half cycles the field collapses and generates very highsecondary voltages which are used to charge the flash capacitor 261. Byway of example, transformer TI may be a Ferroxcube 1408 PA 250-3B7 witha turns ratio of forty-three to one. Transformer TI exhibits a 100microhenry inductance at its primary side and 185 millihenries on thesecondary side. This type of circuit will continue to charge thecapacitor 261 beyond its rating, if not stopped, so a comparator 262 isused to control the oscillator 255. The output of comparator 262 at 263is a logic signal that indicates to component 10 that proper flashvoltage is available. The five-twelve volt supply line 253 is used toenergize oscillator 255 in the circuit of the present commercial instantbar code reader since the oscillator component 255 drives transistor 266more efficiently when running from twelve volts. However, the flashcapacitor charging circuit must also run from plus five volts. Thecircuit of the present commercial instant bar code reader provides arelatively high initial input current of up to two amperes duringcharging of capacitor 261. This only lasts a few milliseconds, but itrequires the host providing power to the reader to be able to handle thehigh current surge. A more uniform charging current over the duration ofthe allowed charge time, say a relatively constant charging current offour tenths ampere over a time interval of about one hundred and fiftymilliseconds would be more desirable. If it is permissible to rechargethe flash capacitor only four times per second, for example, rather thanten times per second, component 10 may be programmed to control thecharge rate to allow the lowest current level, for example, a chargerate of 250 milliamperes over a charging interval of 250 millisecondscould be switched on by the programming where a flash rate of four timesper second would be acceptable.

Much of the flash tube illumination circuit shown in FIG. 9 is used inthe present commercial version of instant bar code reader. The additionof component 16-1 corresponding to flash current interrupter switch 16,FIG. 1, is advantageous to interrupt the flash when sufficient light hasbeen detected by the intensity sensor means 14. Without a means forinterrupting the flash, the flash capacitor such as 266-1, FIG. 8, willbe drained, producing additional unneeded light. Furthermore, thecapacitor will have to be recharged from zero requiring that much morecurrent and elapsed time. Thus, the use of intensity sensor means 14 andswitch means 16 not only reduces the power requirement so as to increasethe operational time of the system in portable applications usingbatteries, but also enhances the performance of the unit by enablingmore rapid flashes of the illuminator means. Input 270 (FLASH VOLTAGEDISABLE) FIG. 8, and input 271 CONT and input 271' (FLASH), FIG. 9, canbe controlled from component 10. Because the output of the xenon flashtube 260 is of such short duration (about twenty microseconds),processor intervention to control integration time is not practical withpresently available processors.

Accordingly, FIG. 9 illustrates a light sensor means 14-1 correspondingto intensity sensor means 14, FIG. 1, as being coupled with the switch16-1 and the illuminator means indicated generally at 15-1 by means of ahardware circuit which can be trimmed for example, as indicated byvariable resistance means 272 associated with conversion circuit andtimer component 273. The circuit of FIG. 9 not only causes a "set"output pulse at 275, FIG. 9, to initiate the shift sequence in the CCDcomponent 11-1, FIG. 5, via input 275-1, FIG. 6, but also stops theflash tube by interrupting the flash tube current utilizing component16-1, which may, for example, be a Motorola Gemfet, type MGP2ON50.Component 16-1 needs to be able to handle the forty amperes peak duringdischarge of capacitor 261.

The microcontroller of component 10, FIG. 1, may be connected to hostcomputer with a six conductor shielded, coiled cable such as indicatedat 122, FIG. 1, by means of circuitry, such as shown in FIG. 10. Theshield should be a braid or spiral wrapped type, but not a foil with adrain wire. Each wire should have a number of twists per inch to give itmaximum flexibility. There are two lines 281 and 282 driven by thereader that can be programmed as ASYNC or SYNC data out, and two linesinto the reader, a line 283 serving as a programmable serial data inline, and a line 284 dedicated as an activelow reset line. The other twolines 285 and 286 are power (plus 5 V) and signal ground.

FIG. 10 shows Fairchild type 74AC14 devices as being utilized for bufferand receiver components 291-295. This component was used because of itsbuilt-in hysteresis and balanced high output drive (24 mA) capability.The various resistors and diodes are used for ESD (electrostaticdischarge) protection up to 25,000 volts. A six-pin connector may beused at 296 of a style similar to that used on industrial camera cables.FIG. 11 shows an implementation 20-1 of the automatic reading distanceadaptation means of FIG. 1. In FIG. 1, a DC motor 103-1 is controlledfrom the microcontroller of component 10 via power c-rivers 302 and 303.The drivers 302 and 303 are selectively energized so as to drive themotor 301 in the correct direction for improving focus. A feedbacktransducer 305 is shown as having a movable tap 306 mechanically coupledwith the focus barrel 30 and thus being driven jointly therewith bymotor 103-1 so that analog to digital converter channel A/D 2 receives aresistance value in accordance with the actual adjusted position of theoptics 30. FIG. 12 shows an implementation 22-1 of reading distancesensor means 22 including an ultrasonic distance measurement circuit 310associated with ultrasonic transducer 38. A disable line 311 (DENB) forthe circuit 310 may be controlled by the microprocessor component 10 ofFIG. 1, and the analog distance measurement value may be supplied viaoutput line 312 to an analog to digital converter channel A/D 1. Allparameter and calibration/conversion tables for the ultrasonic distancemeasurement can reside in the memory of component 10.

The audio indicator of component 120 can be driven from a frequencycreated by the processor of component 10, if desired. All light emittingdiode indicators are controlled by the processor as indicated in FIG. 1.The switch 12 connects to a processor input pin but should be able tointerrupt and wakeup the processor if the reader is in a standby/sleepmode. Label guide indicator means 21 preferably provides two indicatorbeams as previously described, it being conceivable to produce the twobeams from a single light emitting diode which is directed initially toa partially reflecting mirror which is also partially transmissive alongthe length of the photosensor array 13 to a completely reflective mirrorat the opposite end of the array. The marker light emitting diode ordiodes are turned off during the clearing of the image sensor and theenergization of the flashable illuminator means to prevent theirsaturating the image sensor with light and thus interfering with anaccurate bar code reading.

It is desirable to maintain the largest depth of field possible (foreach fixed position of lens arrangement 30) to not only allow easier andfaster focusing, but also to allow focusing on uneven surfaces such asthe curved bar code configuration presented by libel 131 indicated inFIG. 2.

For the purpose of enlarging the depth of focus, and increasing thespeed of adaptation of the reader to a given bar code configuration, thereader housing 10 may accommodate a plurality of adjustable lens meanswith respective overlapping depths of field so that for fixed positionsof the lens means, the depth of field is greatly enlarged. Such multiplelens barrels could be adjusted simultaneously so that the lens systemsin each position thereof have the total depth of field greatly enlarged.As an example, mirror 82, FIG. 3, could have an upper segment bentoppositely to the segment receiving an image at axis 64, so that asecond bundle of reflected light would be directed upwardly as viewed inFIG. 3 toward a second mirror similar to a mirror 83 but with anopposite inclination so that the second image is directed rearwardly inhousing 86 parallel to path 81 but above mirror 82, the second imagepassing through a second lens barrel similar to barrel 90 but located,for example, rearwardly of barrel 90 so as to focus on bar code imagescloser to the window 33, for example, than the barrel 90.

FIG. 13 diagrammatically illustrates the optical components of such anarrangement, which includes a window 33A, a flash tube housing 75A, amirror segment 82A, a mirror 83A, a mirror 84A, a lens barrel 90A, and asensor housing 124A, respectively, corresponding to components 33, 75,82, 83, 84, 90, and 124 of the arrangement of FIG. 3, and providingoptical axes 60A and 64A and paths 80A and 81A, respectively,corresponding to paths 60 and 64 and paths 80 and 81 of FIG. 3. Thearrangement also includes an upper mirror segment 82B bent oppositely tothe segment 82A and receiving an image at an axis is 64B to direct lightupwardly to a mirror 83B having an inclination opposite to that of themirror 83A. A second image is directed rearwardly along an axis 81Bparallel to axis 81A to pass through a second lens barrel 90B locatedrearwardly with respect to barrel 90A so as to focus on bar code imagescloser to the window 33A. One dimensional photosensor arrays 13A and 13Bwithin sensor housing 124A and 124B are connected to control andprocessing means 10A.

Distance measurement means 38 may be coupled with control and processormeans 10A in order to provide range information to processor 10A suchthat the proper focal path A or B may be selected. This may beaccomplished by simply allowing the processor 10A to operatively selecta particular one-dimensional array (124A, 124B).

In another example, a plurality of mirrors analogous to mirror 82 couldbe arranged at respective different distances from the window 33, suchthat all of the image paths would traverse the same lens barrel 90 butthen would be focused onto respective dif f erent image sensors, forexample, by means of multiple mirrors analogous to mirror 84 but locatedat respective different distances from the center of lens barrel 90.Such a multiple image path lens system would, for example, provide pathswithin the reader of length greater than the length of the image path at64, 80, 81, 60 of FIG. 3, and also optical image paths in the housing 86of length shorter than the length of the path 64, 80, 81, 60. Thevarious image paths together could provide the result that the depth offield for each respective image path would overlap with the depth offield of other of the image paths, so that the single lens barrel suchas 90 would cover images anywhere within a range in front of a window 33corresponding to a multiple of the depth of field provided by the imagepath 64, 80, 81, 60 by itself. Thus, through proper multiple mirrorplacement and folding of the optical image paths, a common lens barrelassembly could focus on multiple depths in front of the reader, theprocessor component 10 selecting the respective image sensor or imagesensors from which to assemble the pixels of a complete bar codereading. FIG. 14 diagrammatically illustrates the optical components ofsuch a multiple image path single lens system, which includes a window33C, flash tube housing 75C, mirror 83C, mirror 84C, lens barrel 90C andsensor housing 124C, corresponding to components 33, 75, 83, 84, 90 and124 of FIG. 3, and components 33A, 75A, 83A, 84A, 90A and 124A of FIG.13. The system of FIG. 14 further includes a plurality of mirrors 82C,82D, 82E, 82F and 82G at respective different distances from the window33C, such that all image paths traverse the same lens barrel 90C, to befocused on different image sensors of an array 13C which are within ahousing 124C and which are connected to control and processing means 10Coperative to select the respective image sensor or image sensors fromwhich to select the pixels of a complete bar code reading. With such amultiple image path single lens system arrangement, the leans systemarrangement could remain stationary, avoiding the requirement for amotor and movable parts, and also providing for instantaneous reading ofa label whose various segments came within the depth of field of one ormore of the respective image paths and associated image sensors.Further, distance measurement means 38 may be coupled with control andprocessor means 10C in order to provide range information to processor10C such that the proper focal path C, D, E, F, or G may be selected.This may be accomplished by simply allowing the processor 10C tooperatively select a particular line 13C of the two-dimensional array124C.

II. Description of FIGS. 15 through 44

FIG. 15 is intended as a generic illustration wherein scanning of a barcode label X10 takes place by relative movement between a laser beamindicated at X11 and the bar code label X10. For example, the label maybe moved in a longitudinal direction as indicated by arrow X12, or thelaser beam may be moved in a scanning direction such as indicated at X14for impingement on successive points along a scanning path such asindicated at X15.

By way of example, a laser light source is indicated at X20 andrespective light detectors X21 and X22 are shown for receiving reflectedlight produced by the beam X11 at each successive point along thescanning path X15. By way of example, detectors X21 and X22 may befixedly secured in a housing with the laser source X20 so as to befocused at a common point such as indicated at X15a at a suitabledistance from an end face of the housing. In one type of embodiment withcommon point focus, the label X10 may be moved longitudinally asindicated at X12 so as to effect sequential scanning of the complete barcode. In another example, the housing itself may be moved in thedirection of arrow X14 so that the complete bar code is sequentiallyscanned. In a further example, laser light source X20 and detectors X21and X22 may be pivotally mounted within the housing so as to jointlysweep along the scanning path X15 so as to scan a complete bar code. Inanother type of a scanner, the laser light source X20 is equipped withscanning means for causing the beam X11 to scan along a scanning pathsuch as indicated at X15 at a selected distance from the housing, whiledetectors X21 and X22 are arranged to collect reflected light form eachsuccessive point along the scanning path X15. Alternatively, the laserlight source X20 may be simultaneously illuminate the entire region X15and the detector means X21 and X22 may be pivotally mounted tosequentially scan successive points along the region X15.

In a specific example in accordance with the present invention,detectors X21 and X22 comprise respective light sensors X31 and X32which may be identical, and respective filters X41 and X42 which providegenerally comparable response to sunlight but provide substantiallydifferent responses to the limited spectral band transmitted by thelight source X20, such that an enhanced sensitivity is provided by adifferential between the outputs from sensors X31 and X32.

In the embodiment of FIG. 16, laser light source X20 supplies awavelength of light as indicated at X50 and the filters X41 and X42 havebandpass spectral properties as indicated at X51 and X52.

In the embodiment of FIG. 17, the wavelength of the laser light sourceX20 is indicated at X60 and the broadband spectral transmissionproperties of the respective filters X41 and X42 are indicated at X61and X62.

In each of the embodiments of FIGS. 16 and 17, the ordinate axis mayrepresent transmission between zero percent and one hundred percent. Ineach case, the outputs from detectors X21 and X22 are preferablysubstantially balanced, that is of equal amplitude in the presence ofsunlight alone, the differential in a transmission at the wavelength X50or X60, being at least fifty percent in the examples of FIGS. 16 and 17.

In FIG. 18, there is indicated a scanner unit X70 including a housingwith an end face of X71 which is arranged to confront a bar code labelsuch as indicated at X10 in FIG. 15 at a selected distance such as threeor more inches. In the indicated example of FIG. 18, the laser beam maybe scanned along the length of an elongated window indicated at X73 andmay effect scanning in a plane such as indicated at X74 which wouldinclude the scanning path such as indicated at X15 in FIG. 15.

In the exemplary embodiment of FIG. 18, an array of first and secondlight Detectors is provided with the first detectors such as X21A andX21B and the second Detectors such as X22A and X22B, being arranged inrespective pairs such as X21A, X22A along the locus of reflected lightproduced by the scanning of the laser beam. For the example of two pairsas shown in FIG. 18, and for scanning of the laser beam from left toright as viewed in FIG. 18, during scanning of a left segment of thelabel, reflected light would predominately reach the detectors X21A andX22A. In a mid region of the label, reflected light would reach bothpairs of detectors with comparable magnitude, and for a right-handsegment of the bar code label, the reflected light would predominatelyreach the right-hand pair of detectors X21B, X22B. For each point alongthe scanning path the reflected light reaching a first detector such asX21A of a pair would be of substantially equal magnitude with thereflected light reaching the second detector such as X22A of such pair.

In the specific example of FIG. 18, a common filter element X81 havingspectral characteristics as indicated at X51 or X61 may cover all of thefirst light sensors such as X31A and X31B of the array, while a commonfilter element X82 having the spectral transmission properties X52 orX62 may be associated with the second light sensors of the array such asindicated at X32A and X32B. By way of example, window X73 and filterelements X81 and X82 may form part of the end face X71 of the housing ofthe laser bar code reader unit of FIG. 18, other portions of the endface X71 being opaque, so that light may only enter or exit the housingthrough window X73 and filter elements X81 and X82.

In FIG. 19, laser light source means X20-1 is indicated as comprising alaser source X90 and a suitable scanner sXstem X91 which maX cause alaser beam X111 of a wavelength such as indicated at X50 or X60 to befocused at a point along the scanning path X15-1 and to scan along thepath as indicated by arrow X1 12. For beam positions between thoseindicated at X1 14 and X115, reflected light is predominately receivedby the pair X21B, X22B. For beam positions between X115 and X116,comparable amplitudes of reflected light may reach both pairs X21B, X22Band X21A, X22A, while for beam positions between X116 and X117,reflected light may be predominated at the pair of detectors X21A, X22A.

In the example of FIG. 19, each detector may have an individual filterelement such as filter elements X42A and X42B associated with respectivesecond light sensors X32A and X32B. In FIG. 19, end face X71 may providea common optical window for transmitting the laser beam X111 at a regionsuch as X73, FIG. 18, and for admitting reflected light at regions suchas indicted at X81 and X82 in FIG. 18.

As may be seen each pair of light detectors of the array, such as firstand second detectors X21B and X22B are symmetrically arranged withrespect to the plane X74 of the scanning laser beam so that the pathsfor reflected light from each point such as indicated at X121 along thescanning path X15-1 to detectors X21B and X22B are equal. As in FIG. 19,each detector is shown as comprising a sensor such as X31B, X32B, and afilter Element such as X41B, X42B with respective spectral transmissionproperties as indicated in FIG. 15 or FIG. 17.

In each of the embodiments, as indicated in FIG. 20, the output of thedetector or each detector pair such as X21B, X22B may be supplied to adifferential amplifier means such as indicated at X130A, X130B. Theoutputs of the detector pair X21A, X22A may be supplied to thedifferential amplifier means X130A and X130B may be suitably combinedeither on an analog basis or on a digital basis to provide a resultantbar code signal to be decoded. By way of example, a clock X132 may beconnected with component X131, and with a beam scanner control meansX133 may be constructed and operated so that component X131 candetermine the position of the beam X111 with reference to the zonesX114-115, X115-116, and X116-117, respectively. For example componentX131 may supply pulses derived from clock pulses to component X133 todrive the scanning operation. Alternatively, beam driving pulses may begenerated at component X133 and supplied also to component X131.

It is contemplated that the present embodiments will provide a morereliable bar code reading with a given laser source and under naturaland supplementary lighting conditions, and further may allow the use ofa lower power laser light source, with many attendant benefits such asgreater safety, better adaptability to portable (battery powered) andhand-held use, less heat to dissipate, and therefore expected longerlife. A differential between the outputs of detectors such as indicatedat X21 and X22 will provide superior noise rejection properties incomparison to a detector such as X31 by itself. If necessary, a neutraldensity filter could be combined with one or the other of the filterssuch a X41 and X42 to balance the detector outputs under broadbandillumination (e.g. sunlight).

FIG. 21 shows a hand-held wand type scanner X100 according to FIG. 15 orFIG. 17 wherein a light emitting diode or other narrow band light sourceX120 produces a band of light for example in the infrared region. Inthis case, wavelength X50 or X60 may be of the order of X910 manometers,and light sensors X131 and X132 may be particularly sensitive at thiswavelength. According to the example of FIG. 15, filters X141 and X142save passbands as indicated at X51 and X52 respectively, while accordingto the example of FIG. 17, the filters X141 and X142 have overlappingwideband characteristics as indicated at X61 and X62. In each case, theoutputs of the light sensors X131 and X132 may be supplied todifferential amplifier means such as X130B, FIG. 16, so as to provide aresultant output especially sensitive to a bar code scanned thereby evenin the presence of ambient daylight illumination.

In one embodiment according to FIG. 21, light is transmitted from lightsource X120 to a light port X144 via optical fibers X145, and reflectedlight is transmitted via respective optical fibers such as indicated atX146 and X147 which terminate at a small-area central region of lightport X144. By way of example, the reflected light transmitting fiberssuch as X146 and X147 may be essentially uniformly distributed at theport X144 over a central circular area which is small in comparison tothe size of a minimum width bar of a bar code to be scanned, so thatambient light has less effect on resolution than where the size of theincident light spot is relied upon to define scanning resolution.

Where lenses are utilized, the reflected light is preferably collectedby symmetrically arranged lenses focused at a common reflected lightpickup region at the bar code for high resolution scanning of the barcode. (The pickup region may have a small diameter in comparison to aminimum bar dimension). Preferably in this case also equal amounts ofreflected light are transmitted to respective photodetectors such aX131, X141 and X132, X142. Again it is preferred that the reflectedlight optics provide the required resolution independently of the sizeof the incident light spot from the light source such as X120 so thatresolution is less affected by the presence of intense ambient light.

Preferably in each case the response characteristics of the detectorswith respect to reflected light are so matched that the first and secondlight sensors such as X131 and X132 provide essentially equal signalswhen the light source X120 is not energized and the light port X144 isheld against the bar code, for each incremental position of port X144along the length of the bar code, even in the presence of sunlight.

Light source X120 may be a conventional light source for a wand typescanner such as a light emitting diode, or may be a laser light source.

It will be apparent that many modifications and variations may beeffected without departing form the scope of the novel concepts andteachings of the present invention.

A. Description of FIG. 27

FIG. 27 is a diagrammatic view showing a target region for an instantbar code scanner such as a moving beam laser scanner, wherein a visiblelaser diode of the scanner is pulsed in synchronism with beam deflectionto generate one or more visible markers in a marker beam mode.

A laser bar code scanner as shown in FIGS. 15-21 may generate markerspots such as shown at X13-41, X13-42. Laser beam scannersconventionally generate a start O scan rectangular waveform as afunction of scan motor operation. The start of scan waveformcorresponding to X-axis deflection can be used to momentarily turn on avisible laser diode source at the beginning and end of each high rate(X-axis) scan to product marker spots X13-41 and X13-42.

In marker beam mode it is preferred that the electronics associated withthe photodetector, e.g., as indicated in FIG. 20 be deenergized, e.g.,to conserve battery power where the scanner is battery powered. Amomentary push button switch (such as indicated at 68 in U.S. Pat. No.4,251,798) or the conventional trigger of pistol shaped visible laserdiode scanners may produce a logical signal (e.g. zero volts or groundpotential) when actuated, which signals for marker beam mode. In aninitial mode before actuation of the manually operated actuator, thescanner may be deenergized. Operation of the manual actuator mayestablish marker beam mode for as long as the actuator is held inoperated condition. In marker beam mode, the scanner mechanism isoperated at a suitable rate, e.g. 36 scans per second. For scanning atdistances over two feet, the rotary drive could operate at two scans persecond to give brighter marker spots. The rotational speed could be slowat the beam turn-on marker intervals, and faster between markerintervals.

Where the scanner is vehicle mounted, or mounted on a manually propelledwheeled device for example, the number of horizontal lines in thescanning raster may be increased, e.g., to 240 or more. Where a completeraster is scanned quickly, or where the scanner may be otherwise heldsteady during scanning, the area array matrix type photosensor of FIGS.45 and 46 may be used with a laser beam raster scanner. The laser beammay in such case be of oblong cross section with a Y-axis dimension of,e.g., 40 mils (0.040 inch ) so as to cover a given height of raster withfewer horizontal scan lines. The raster may comprise interlaced fieldsof horizontal scan lines with the first field beginning with a tophorizontal line and the second field beginning with a lowermosthorizontal scan line. The brightness of the scanning beam may becontrolled during scanning so as to compensate for any lack ofuniformity in the sensed intensity of the image over the photosensorarea, e.g., due to elapsed time between scanning of different imageregions and varying label distance (e.g. due to curvature or the like).A convenient way to modulate light intensity from the laser diode is tosupply a high frequency pulse Train to energize the laser diode in afrequency range far above the highest information rate, and to vary suchhigh frequency to compensate for nonuniformities (detected, e.g. b)yintensity sensors such as X50, X51, X52, FIG. 16 located, e.g., toreceive reflected light during a first horizontal scan line above thebar code information where the sensors are activated at the marker beamintervals, and then outputs stored digitally and compared).

A scanner such as shown in U.S. Pat. No. 4,251,798 may have a matrixtype photosensor and optical system located generally in the filter andphotodetector region (58,60, FIG. 2 of U.S. Pat. No. 4,251,798). Byusing a laser diode source, the housing may be more compact, so as tohave the configuration, e.g., of the housing of FIGS. 29 and 30. Ahandle may be detachably secured with the laser bar code scanner (e.g.as shown in FIG. 33), and/or the laser bar code scanner may be vehiclemounted by means of a universal mount such as shown in FIG. 35. Theuniversal mount may be clamped to the forward part of the scanner (nearreference numeral X19-13 in FIG. 29 where the handle with push buttonactuator (X19-90, FIG. 35) is also present. The universal mount may beof sliding friction 30 type so as to sustain any orientation to which itis moved (e.g. by manipulation of the handle while aiming, e.g., througha view port in marker beam mode).

Where the scanner is to operate according to FIGS. 15-21, for example,the intensity of the marker spots such as X13-41 to X13-42 may beadjusted in marker beam mode by actuating one of a series of intensityselection keys located on a keyboard (such as 24, sixth figure, U.S.Pat. No. 4,251,798 or at X11A, X11B, FIGS. 36-37). The intensityselection keys may progressively increase the energizing frequency forthe visible laser diode (such as X20, FIG. 15 hereof, or X90, FIG. 19hereof.

When the actuator is released to shift from marker beam mode to symbolreading mode, the same energizing frequency may be used for the visiblelaser diode as was selected in marker beam mode. Thus, the laser beamwill be relatively more intense in symbol reading mode where thedistance to the bar code is relatively great and/or where the ambientillumination is relatively intense.

In a preferred symbol reading mode, the scanner does not revert toinitial mode automatically when a single bar code line has beensuccessfully read. In one example with a single line bar code scanner,the scanner may be manually displaced to read a stacked bar code. Inthis example, a beeper or other indicator will indicated a successfulreading of a first line of the stacked bar code whereupon the scannerremains in symbol reading mode and the operator may manually tilt thescanner to read further lines of the stacked bar code. If desired uponeach successful read, the marker spots, e.g., X13-41 and X13-42 for asingle line scanner may be flashed after each reading of the same barcode line (e.g. with the photodetector electronics deenergized duringsuch flashing) so as to indicated to the operator that the scanner isreading the same line and ignoring (not storing) the result of suchreading. For example, if the scanner mirror has ten facets and isrotated at ten revolutions per second, and if after a successful read ofa line the scanner performs nine scans with no new bar code number beingread, on the tenth scan the photodetector electronics would beautomatically deenergized and the marker spots X13-41 and X13-42flashed. The system would then execute nine further scans with thephotodetector system activated. If the further scans revealed anon-bar-code-reading condition consistent with scans occurring betweenbar code lines, the tenth and further scans could all be with thephotodetector active. After, for example, ten consecutive non-bar-codescans, the scanner might accept a bar code reading of the same value asthe last reading accepted, (the operator being informed to avoidreturning to a previous read label unless such label was to be read andentered a second time).

Where the bar code scanner is progressively tilted to read a series ofbar code lines, a beep or other indication will occur each time a newbar code value is registered. After a suitable number of such beeps,e.g. five, the system may be returned to initial condition, e.g. by arapid manual operation and release of the manual actuator, or theactuator may be operated, e.g. to disable the photodetector electronicsand return to marker beam mode to assist in aiming at a new symbol to beread, while conserving in power supplied to the visible laser diode andavoiding unnecessary power consumption by the photodetector electronics.

Where, for example, the scanner is supported by a sliding friction typeuniversal mount while being manually aimed, a key may be actuated toproduce only a single, e.g. central marker spot such as X13-50, FIG. 27.(This is somewhat analogous to the static PSC mode, col. 12 of U.S. Pat.No. 4,251,798, except that preferably in the present embodiment thescanner motor is operating at a desired speed, and the visible laserdiode is flashed for, e.g., ten percent of each scan interval at the midregion of each start of scan half cycle). While the central marker spotX13-50 is on the background color of the bar code, e.g. just above thebar code, the marker spot may be adjusted to a suitable intensity bymanual selection from a group of marker beam intensity selection keys,or the photodetector may be momentarily switched on by a separatecontrol key to automatically adjust the energizing frequency of thevisible laser diode for proper reading operation. For example, amicroprocessor used for decoding may have a program for automaticallyeffecting energizing frequency adjustment to provide a suitablephotodetector output when the control key is momentarily operated tocause the marker beam to generate a central marker beam spot. Theprocedure could be carried further by having left and right marker beamspots as well as a central one, the control program determining properminimum laser diode energizing frequency suitable to the three markerspot locations, or if desired determining a suitable variation of laserdiode energizing frequency as a function of beam displacement tomaintain essentially uniform illumination of the bar code during asubsequent symbol reading operation. As an alternative, when theactuator is released from marker beam activating position, it may beassumed that the marker spots are aimed at background, and in a firstcycle with the visible laser diode energized for a complete scan (ormomentarily held in three marker spot mode) the photodetector is turnedon and the control program progressively adjusts laser diode energizingfrequency until a suitable frequency level or frequency variationpattern is set, whereupon the decoding program is enabled, and the usermay progressively scan a series of bar codes with similar background anddistance from the scanner.

After completion of scanning of such a group of bar codes and return toinitial mode, the adjustment procedure may be automatically repeatedeach time the actuator is operated to marker beam mode, and thenreleased to symbol decode mode. At each turn off of the scanner, e.g.,by quick-actuation-and-release of the actuator, the scanner may berestored to an initial condition such that any new operation of theactuator will result in a selected average energizing frequency for thelaser diode energization being reestablished.

B. Summary Description of One Exemplary Embodiment According to FIG. 27

Because of the relatively low power consumed in marker beam mode, it iscontemplated that a battery powered scanner may be detachably coupled toa belt-carried sliding friction type universal support, with operationessentially corresponding to that with the universal support mounted ona vehicle, e.g. a forklift truck. In each case a pistol-shaped scanner,e.g., of the single line scanning type can be aimed by manipulation ofthe scanner handle while observing the corresponding movement of themarker spots.

With the marker spots such as X13-41, and X13-42 on the symbolbackground above the symbol, the manual actuator may be released toinitiate an automatic adjustment of visible laser diode energizingfrequency, the decode microprocessor and photodetector electronics beingenergized at this time. Once the photodetector is receiving adequatereflected light intensity from each of the marker spots such as X13-41,and X13-42, FIG. 27, the scanner automatically switches to symboldecoding mode and the user will see a complete scan line, e.g. X13-70.Thereupon the user gradually tilts the scanner to successively scan aseries of bar code lines, e.g., of a stacked bar code symbol or othertwo dimensional optically readable information set. As each line (orportion) is successfully decoded, the scanner may emit a single beep.When the user has heard, e.g., five beeps, the actuator may be quicklyoperated and released to restore the scanner to initial deenergized modeand to reset visible laser diode energizing frequency so that it will beat a desired initial marker beam value when the scanner is againactuated to scanner beam mode. By way of example the initial marker beamfrequency may be intermediate the available maximum and minimum values,and may be adjusted by a series of selection keys as previouslydescribed. In this way the need for automatic adjustment of laser diodeenergizing frequency at the beginning of symbol scanning mode is reducedor even eliminated.

Normally in this embodiment, the number of laser diode energizingfrequencies need not be large since a major purpose in not using themaximum safe frequency at all times is to conserve battery power.Another objective of adjusting the laser diode energizing frequencywould be to avoid saturation effects when reading close-in bar codesymbols. Battery power may be coupled to the scanner through the beltmount therefor where the battery pack is supported on the belt, forexample. The scanner may contain its own battery pack, e.g. in thehandle, where it is to be operated detached from the belt mount in acompletely hand-supported mode.

As previously described, in symbol decoding mode, a single beep issounded for each new bar code value which is read and stored. A givenvalue is stored only once unless there is a selected number ofnon-bar-code scans (e.g. ten) intervening between the lastclose-following reading of the given value, and the new reading of suchvalue. The same value is registered again also whenever a differentvalue or values are registered during intervening readings. If thescanner is left in symbol reading mode, provision may be made forreturning to initial mode, if a selected number of scans arenon-bar-code scans (e.g. result from the scanner being pointed at thefloor or some other non-reflective or uniformly reflective target area).The scanner may also return to initial mode if the actuator is notactuated e.g. for twenty seconds regardless of how recently the scannerhas registered a valid bar code reading since normally only five or soreadings would be made during a given symbol reading operation. Wherebelt-mounted, the scanner can be automatically reset to initial modewhen the belt is opened to remove it from the wearer. On a vehicle, thescanner can be deenergized when the vehicle ignition switch is off. Thecoupling between a scanner and a universal mount may include anautomatic coupling of the scanner to a set of contacts-analogous toautomatic couplings as disclosed e.g. in FIG. 38, for transmittingcharging current, data signals and the like.

C. Description of FIGS. 22-25

As an example, the single line laser bar code scanner of U.S. Pat. No.4,820,911 may be operated according to FIG. 22. This patent may bemodified to utilize the teaching of FIGS. 15-21 by inserting a beamsplitter X801 in place of a band pass filter (59, second figure of U.S.Pat. No. 4,820,911), with filters X802 and X803 and photodetector X804.The filters X802 and X802 may be either low pass, high pass, or bandpass as discussed with reference to FIGS. 15-21. In this examplephotodetector X804 would be matched with photodetector X8-52 for optimumcancellation of the signal component due to ambient illumination.

As another example, the mirror facets such as X8-24 could be of dualslope, the position of X8-34 being adjusted downward, e.g., by a beamdiameter to maintain a horizontal output beam axis just below centeraxis X805. Then a collector corresponding to X8-54, X8-52 could bearranged above the horizontal exit beam path X805 and associated withfilter X803 and photodetector X804, the beam splitter X801 beingomitted.

D. Description of FIGS. 23, 24, and 25

FIG. 23 shows such a mirror X9-24 with a second visible laser diodeX9-34A of the same wavelength (or a different wavelength where beamsplitters and two pairs of filters and photodetectors are used). Thesecond visible laser diode is mounted in an upper section of the housingand its associated components are shown arranged as a mirror image ofthe lower components X8-34, X8-46, X8-54, X8-56, X8-64, X8-70, X8-74.These components could be accommodated by a housing X910 with akeyboard/display region X911 such as indicated in FIGS. 36-37.

The laser diodes X8-34 and X9-34A, FIG. 23, could be operatedsimultaneously in a variable frequency energizing mode, the two outputbeams X9-15 and X9-15A being offset, e.g., vertically to provide adouble simultaneous scan line for example. The beams could havedifferent configurations, e.g., circular and elliptical, and beactivated during respective alternate scans, or the beams could beselectively activated individually, jointly, or alternately by means ofmanual key selection, e.g. using the scanner keyboard of FIGS. 36-37.

Where the scanner of FIG. 23 is equipped with symbol distancemeasurement means, e.g. actuated by a key when the marker spots frombeam X9-15 and/or X9-15A are aligned with a bar code line (or using e.g.one marker beam such as X9-15 in marker mode), the distance measurementmay be used to select which beam to activate, or whether to activateboth beams for proximity detect mode.

FIG. 24 shows the beam pattern comprising beam spots X1015 and X105A ata reference plane indicated at X1020 for the case of two circular beamsof equal diameter separated by a center to center distance approximatelyequal to beam diameter. With this embodiment one half-power beam couldbe used for close-in scanning, and an automatic distance measurementcould control selection of one or two half-power beams (e.g. in adefault operating status) for symbol decoding mode and/or proximitydetect mode. The distance measurement could be based on time betweenmarginal marker spots in comparison to bar code line width, or could bebased on the reading distance sensor means Y25-22, FIG. 52, or X26-1,FIG. 40.

It is also conceivable that the beams would produce respective spotsX1115, X1115A as shown in FIG. 25 at a reference plane such as indicatedat X1120. Here again switching between the beams could be based on adistance measurement where dense bar codes are generally in a close uprange, and coarser bar codes are generally to be read at greaterdistances. Where half-power laser diodes are used, both the beams ofFIG. 25 could be on simultaneously at relatively great throw distancesat least during alternate scans or the like.

As another example, the reflector X8-54 may be mounted external tohousing X8-10, for example above the housing and facing generallyfrontally (and without a center aperture), the parts X801-X804 and X8-52being mounted external to the housing and forwardly of the externalreflector to receive reflected light for each successive beam positionalong a bar code. Where reflectors such as X8-54 are positionedexternally, above and below housing X8-10, elements X8-52, X802 may beforwardly of one reflector and above the housing, while components X803,X804 may be located below the housing and forwardly of a secondreflector. The reflectors and associated photodetector assemblies may bemounted on an adapter which fits over the front of the housing X8-10without obstructing window X8-48.

E. Description of FIG. 26

In FIG. 26, the output spectrum for a laser diode, e.g. in the infraredregion, is indicated at X1210. Curve X1211 indicates the relativespectral response of a selenium photovoltaic material while curve X1212is for a silicon photovoltaic material. In FIG. 22 or FIG. 23, it ispossible that the filters such as X802, X803 could be omitted where thephotodetectors X8-52 and X804 had respective spectral responsecharacteristics as represented at X1211 and X1212. A similar resultwould be possible for a visible laser diode X8-34 operating at awavelength of about 0.5 microns (500 nanometers).

Such an approach would also be applicable to the embodiments of FIGS.15-20, again suggesting that filters such as X41, X42, etc. may not beessential to obtaining a substantial degree of ambient lightcompensation.

F. Exemplary Operation of the-Embodiments of FIGS. 22-27

In a mode of operation of the embodiment of FIG. 22 or FIG. 23,alternate scans during reading operation may take place with the laserdiode deenergized. The output of the photodetector system such as X8-52,X801-X804 (or 52, 59, in the second figure of U.S. Pat. No. 4,820,911)may be sampled, e.g., at a rate many times greater than the maximuminformation rate, and the result stored for use in modulating theintensity of the laser beam during the next scan so as to tend tocompensate further vertical reticle line X14-21 which is vertical whenthe laser beam is scanning in a perfectly horizontal plane. It is thusapparent to the user if the beam is not scanning along a pathperpendicular to the bars of the bar code. Where the scanner handle isguided by a receiving sheath such as X981 may be mechanically guided bya universal mount on a fixed support (e.g. a forklift); then it is asimple matter for the user gripping the handle X9-16 and sheath X981 toadjust the scanner so reticle X14-X21 is essentially parallel to thebars of the bar code. A center marker spot X13-50 between spots X13-41,X13-42, would facilitate visualization of the central part of the barcode through view window X14-20.

FIG. 28 indicates the use of a linear array X1462 of photodiode elementsX1463 in front of a straight optical collector X14-54 (by way ofexample). A printed circuit board X1464 may carry the array or arraysand conduct the parallel outputs to suitable processing circuitry suchas described with reference to FIGS. 29 and 30. For a uniformly straightreflector configuration (e.g. as represented at 76 in the third figureof incorporated U.S. Ser. No. 07/422,052, with the sensor arraysextending along the axes of elements 35, 36, the second figure), thereflector may comprise two or more straight sections (analogous toelements 35, 36 the second figure of Ser. 07/422,052), with cooperatingstraight line array sections such as 1462. Each reflector is preferablyshaped for optimum efficiency at the maximum range of the scanner.

G. Description of the Embodiment of FIGS. 29 and 30

FIG. 29 is a partial longitudinal sectional view of the scanner of FIG.22, with a slip-on external photodetector assembly X1520 applied to thefrontal barrel portion of housing X8-10. FIG. 30 is somewhatdiagrammatic horizontal sectional view for illustrating details of theexternal photodetector assembly X1520 of FIG. 29 and cooperative partsof the scanner of FIG. 22.

In FIG. 29, upper and lower straight continuous reflected lightcollectors X1554 and X1555 are shown, collector X1554 being designed tofocus reflected light from a near reference plane X1556 at a photodiodearray X1562 which may correspond identically with array X1462. ArrayX1562 may have a width corresponding to housing X8-10, e.g. about threeinches. Reference numeral X1511 designates a ray of reflected laserlight reflected from a small illuminated spot on a bar code at the nearreference plane X1556.

At a further reference plane X1557, e.g. representing an optimum planewith respect to scanning of a less dense bar code a reflected light rayX1512 at the laser wavelength may impinge on a second photodetectorarray X1563. A reflected light ray X1513 from a bar code at anintermediate location indicated at X1558 is shown as impinging on afurther photodiode array X1582, while a ray X1514 reflected from a barcode at a farther location is shown as impinging on a further photodiodearray X1583.

The entrances to reflectors X1554 and X1555 may be suitably covered bymaterial transparent to the laser wavelength as indicated at X1585,X1586.

The methods previously described may be used in addition to bandpassfilters at X1585, X1586, or in places thereof. Thus the arrays X1562,X1563, and X1582, X1583 may be covered by respective filters asrepresented in FIG. 16 or FIG. 17, so that the respective differentialoutputs from the upper and lower photodetector arrays each tends tominimize the effect of ambient light.

Battery power X1590 can be coupled to the scanner from the subassemblyX1520 via external contact bars embedded in housing X8-10 andcooperating spring fingers analogous to the fingers (632, seventeenthfigure or 801, twenty-fifth figure of incorporated U.S. Ser. No.07/347,602). In this case, photodetector output signals from detectorsX1562, X1563, X1582, X1583 could also be coupled via such spring fingersand housing contracts to the interior of the scanner.

In this case, the subassembly X1520 can use its own battery power, e.g.as indicted at X1590 for supplying power to differential amplifiers andphotodetectors for arrays X1562, X1563 and X1582, X1583. As anotherexample, the difference signals can be converted to optical form e.g. atX1592, X1593 for transmission through the margins of window X8-48 torespective receives X1594, X1595.

A battery pack may be used for X1590 as described in Steven E. Koenckapplication for patent "Battery Including Electronic Power Saver" U.S.Ser. No. 07/433,076 filed Nov. 7, 1989, Attorney Docket No. 6881.

The assembly X1520 may be longitudinally adjustable on the barrel ofhousing X8-10, a second position of assembly X1520 being indicated indot dash outline at X1520A. The external contact bars embedded inhousing X8-10 may be elongated to maintain engagement with thecooperating spring fingers of assembly X1520 in the various adjustedpositions.

In the embodiment of FIG. 22, a single detector X8-52 may be used with arotating filter disk serving to interpose filters such as X802 and X803sequentially and cyclically into the reflected light path at a ratehigher than the maximum information rate. The differential betweenrespective pairs of output signals generated by the respective types offilters may be generated, e.g., by a sample-and-hold-circuit for holdinga first occurring sample, so that the delayed first signal and a secondoccurring signal can be supplied simultaneously to a differentialamplifier. The output of the differential amplifier can then be sampledduring the second signal to generate a sampled bar code output signalcompensated for ambient light.

H. Discussion of a Presently Preferred Scanner System with ProximityDetection

The general prior art for actuation of most CCD and laser scanners hasrequired the use of an actuation switch or trigger to initiate operationof the scanner. This method has been used by NORAND CORPORATION forarray type readers as shown by incorporated U.S. Pat. No. 4,894,523. Seealso U.S. Pat. No. 4,282,425 (filed Jul. 25, 1979 and also disclosingproximity detection). Such prior art scanners depend on the operatorpulling the trigger or depressing the actuation switch at the correcttime, presumably when the reader is correctly positioned in front of thelabel. If this is the case, the reader will be activated, perform theread and automatically terminate operation quickly and efficiently andsubsequently shut down to conserve power. In the case of moving beamlaser scanners, it is probably more likely that the operator will pressor activate the trigger to generate the reassuring "red stripe" or lineand then position the reader so that the "red stripe" reading beamcrosses all of the bars for a proper read. When the laser scanner isused in this way, obviously significant power is wasted operating thelaser and the motor when no target is available.

It is possible to make an improvement to trigger actuated scanners byadding an electronic proximity sensor to be used either with or withouta trigger switch. The idea is to use a sensor that detects the presenceof something (such as a label) before the scanner is actuated. If thisis used with a trigger operated scanner, the concept would be to actuatethe sensor with the trigger switch, and as soon as the sensor detectsthe presence of a label, the scanner runs. If this is used with ascanner with no trigger, simply placing the reader in front of a labelso that the sensor gets the proper indication will cause the scanner tooperate. The trigger operated version would be the most power efficientand probably work best because it would include a double indication thatreading should occur.

Given some combination of a trigger and a proximity sensor where thetrigger causes the proximity sensor to begin operating and thesuccessful sensing by the proximity sensor of a target label causes thescanner to operate, it may be possible to further improve the powerefficiency of a scanner such as moving beam laser type.

I. Exemplary Sensing System

The most obvious and direct approach to sensing is to utilize thecombination of a light source and light detector where a reflectivelabel causes a signal to be received by the detector. The generalarrangement is shown in FIG. 41. In the general case, proximity isdetermined by the level of the signal as received by the light detectorX27-10. Experience has shown that this has some inherent problems suchas noise, ambient light, and device offsets or errors. Several methodsmay be employed to improve the detection of the proximity sensed signal.One method might be to pulse the light source with a narrow, highintensity pulse and look at the detector at that time in comparison tothe non-energized condition. The signal waveforms might be representedas shown in FIGS. 42A, 42B, and 42C. This method allows variation inambient light or noise to be removed differentially as well asaccounting for sensor device and circuit variations.

Additionally, the ambient light level may be determined and opticallyreadable information sets may be located by (1) taking a first reading(laser+ambient) and producing a first signal, (2) taking a secondreading (ambient only) and producing a second signal, (3) producing athird signal corresponding to the value of the first signal less thesecond signal, and (4) comparing the third signal to a predeterminedthreshold value in order to determine whether a bar code is present andwhether the scan driver should be activated.

Thus, optically readable information sets may be located and read withminimal power usage by (1) positioning the scan driver such that laserlight from the laser is directed along a path generally coordinated withan aiming axis of said scanner; (2) pulsing the laser such that thelaser light beam is reflected from the positioned scan driver anddirected along a path generally coordinated with an aiming axis of thescanner such that the laser light beam is at least partially reflectedfrom a potential optically readable information set; (3) reading thereflected laser light beam partially reflected from a potentialoptically readable information set by sensor means such that a firstoutput signal is generated which corresponds to the first illuminationlevel of the potential optically readable information set illuminated byboth ambient light and the laser beam pulse; (4) pausing a finite periodof time; (5) reading the illumination level of the potential opticallyreadable information set a second time via the reading sensor means andgenerating a second output signal corresponding to the secondillumination level; (6) comparing the first and second outputs such thata third output signal corresponding to the intensity of the partiallyreflected laser pulse is generated; and (7) activating the scan driverand the laser if the third output signal exceeds a predeterminedthreshold value.

In another preferred exemplary embodiment of the present inventionoptically readable information sets may be located and read with minimalpower usage by (1) positioning the scan driver such that laser lightfrom a laser is directed along a laser beam path generally coordinatedwith an aiming axis of the scanner; (2) modulating the laser light; (3)pulsing the modulated laser light such that a modulated laser light beamis reflected from the positioned scan driver and directed along a pathgenerally coordinated with an aiming axis of the scanner such that themodulated laser light beam is at least partially reflected from apotential optically readable information set; (4) reading the reflectedmodulated laser light beam by a reading sensor and generating an outputsignal in response thereto; (5) filtering the output signal to removeambient noise; and (6) activating the scan driver and the laser if thefiltered signal exceeds a predetermined threshold value.

Another technique that may be used to increase the sensitivity of theemitter-detector system is to send a modulated pulse of light toward thetarget area and tune the detector and amplifier to that modulatedsignal. In essence, this is an RF-like signal processing methodutilizing a narrow high gain bandpass amplifier that only responds tothe known signal frequency. In this case, the filter bandpass width willdetermine the potential response time of the detecting mechanism. Thesignal waveforms might be represented as in FIGS. 43A and 43B. Forpurposes of implementation simplicity, the pulse modulation frequencymight be 455 kHz corresponding to the low cost and widely availableradio IF components such as ceramic filters and IF processing integratedcircuits.

Further benefit might be realized by combining both methods includingpreviously described pulse on/sense, pulse off/sense techniques alongwith the modulated pulse technique. It is possible that the combinedmethod may be needed to provide the high sensitivity needed withrelatively weak illumination.

One of the general areas of technical concern is in "timing" the sensorso it is able to discriminate between a label placed or positionedcorrectly for reading, and some distant or non-label object such as adistant wall or ceiling. At a minimum, the performance of a scannerproduct would be enhanced if reading only commenced if something thatmight be a label had to be detected before the high-powered reading modewas activated. In this case, the sensitivity need be such that it alwaysreads for a label, and it might "accidentally" read for a non-labelunder some, but presumably not all conditions.

There is another general approach to this problem using some of thepreviously suggested concepts. Particularly in the case of laserscanners using VLD (visible laser diode) light sources, it is possibleto pulse the VLD rapidly and detect the reflection from a target by thescanner optics. If appropriately designed control circuits areintegrated into such a laser scanner, it may be possible to use the scanoptics to implement the target sensing function. There would be severalbenefits to this approach.

1. The system would be less costly since there would not be duplicationof the light source and detector components.

2. The label targeting effect would be more accurate since only a singlelight path would exist, rather than two or more for physicallynon-obstructive positioning of the additional emitting/sensingcomponents.

3. The system would be physically smaller if no additionalemitting/sensing components and signal processing circuits are needed.

4. As in the separate emitter/detector examples, this system wouldoperate by being placed in an activated "label-seeking" mode which wouldcause the VLD to be activated in a low duty cycle (and hence low averagecurrent consumption) mode, and would attempt to detect a signalcorresponding to the reflection from a label. Once this reflectionsignal is detected, the scanner would be placed in an active scanningmode similar to the typical trigger activated types.

The proximity signal processing mechanism might be either of the typesdescribed previously, or it might be processed directly through theactual scan signal processing circuits. In the "label-seeking" mode, thebandwidth of the detecting amplifier need not be nearly as high as inthe active scanning mode, so bandwidth modification may be employed toadjust the amplifier bandwidth according to the mode in progress.

One key physical characteristic of the label sensing method is that thebeam deflection system should preferably stop or rest in a position suchthat the emitted beam exits essentially straight forward, and not at anangle to either side as illustrated in the top view of FIG. 44. Thesensor beam X30-11 may be positioned slightly off center, e.g. withinthe indicated crosshatched area with angular extent X30-12. If it islocated far to either side, it may miss the label resulting in improperoperation. Two basic beam detection methods (at least) may employ thissensing technique. The simplest method involves the vibrating mirrortype with a torsion spring that hold the deflection mirror in itsgeneral centered position. Even if vibration causes the beam to moveslightly, it will still generally be located with the indicatedcrosshatched arc.

The rotating polygon mirror deflection methods are somewhat morecomplex. Unless it is controlled, the motor that spins the rotatingmirror will generally stop in randomly distributed locations. To causethe beam to exit straight out of the unit, some means must be providedto control the rest position of the motor. Ideally, any facet of themirror might be used for the sensing beam, although it may be necessaryto select one single facet and sequentially drive the motor in "steppermotor"-like fashion. This may be made possible by the use of aHall-effect motor whose coils are driven in response to magnetic sensingof the rotor position. If drive circuits with sufficient intelligenceare used, the motor may be sequentially driven until the exactrotational position is reached. This may require a reduced ramped-downdrive speed to decelerate the rotor such that the rest position isaccurately and repeatedly reached.

Other methods of stepping the rotor into a predictable position may alsobe employed. One might be to select an integer-related number of facetscorresponding to the number of coils. By pulsing or selecting one of thedrive coils, it is possible to hold the rotor in a fixed position. Themagnetic poles of the motor permanent magnet may be determined byappropriately designed field/flux techniques so that its spacialposition may be indicated for proper assembly in production.

J. Supplemental Discussion

Instead of using two detector-filter systems as in FIGS. 22 and 23, itis conceived that a single detector may be used if the light supplied tosuch single detector from the scan mirror system is alternately thatrepresented by the respective curves X51, X52 in FIG. 16, or X61, X62,FIG. 17. Thus, with a rotary scan mirror with a plurality of facets asrepresented at X91, FIG. 19, or X8-24, FIG. 22, alternate faces of thescan mirror could be optically coated to reflect the respective bandssuch as X51, X52 or X61, X62.

The electronics associated with the single detector would then digitallysample and store one scan line and differentially combine it with thecorresponding successive samples of the next scan line (e.g. alsoconverted to digital samples) to compensate for ambient light. With thisarrangement in FIG. 23, single detector X8-52 could operate in thismanner while beam X9-15A was off, for example, or each detector of FIG.23, could operate individually to compensate for ambient light in itsparticular field of view.

Alternately, it might be possible to coat, e.g., the upper half of eachmirror face X8-24, FIG. 22, and to utilize two detectors one above theother for receiving reflected light from the coated and uncoated halvesof each mirror, respectively. This could also work with an oscillatingmirror collecting reflected light.

It is also conceivable to use rotary facets which are transmissive as toone band of wavelengths such as X52 and reflective as to another bandsuch as X50, with one sensor behind the active facet position, and asecond sensor in front of such facet position.

III. Description of FIGS. 45-54

A. General Explanation of a Preferred Embodiment of the Invention

The biggest negatives surrounding the use of portable Optical CharacterReader (OCR) systems have related to the inherent weaknesses of theavailable hand-held s scanner technology. The purpose of the describedinvention is to substantially improve the performance and capabilitiesof hand-held OCR scanners so that this inherently convenient codingmethod might once again become a viable alternative for automaticidentification applications.

The invention consequently seeks to eliminate the need for accuratelyaligning the reader with respect to the codes to be read. An OCR devicein accordance with the invention would therefore desirably include aprovision for instantaneously illuminating a region exterior to thereader which region contains the combination of codes or characters tobe read. Thus during a single instance of illumination, the selectivereflection representing relatively darker and lighter elements of thecode configuration to be read may be imaged or focused with suitableoptics at an interior region within the reader, the interior regionbeing referred to also as an imaging area. An array of photosensorelements is disposed at the interior imaging area. The photosensorelements receive during that instant of illumination from anyinformation at the exterior region a complete light image or opticalimage at the interior region. The instantaneous transfer of the image tothe imaging area substantially eliminates risk of error due to anoperator causing an inadvertent movement of the reader. A possiblesource of error in aiming was recognized, however. Such source of errormay be minimized, if not totally eliminated, when an operator uses amarker source as provided in accordance with the invention. According tothe invention it is, consequently, contemplated to identify or mark theregion from which optical information would be transferred to the areaarray of photosensor elements or photosensor array.

As a specific example, marker beams originating from light sources atthe four corners of the photosensor array may be projected via suitableoptics onto a supporting surface carrying the information, such as alabel, to be read. The beam of the light sources may be shapedoptically, such as by non-spherical lenses associated with the lightsources to linearize the mark spots impinging the surface containing theinformation. In the case of a marker beam of elongate, linearized crosssection, the light sources need not be located at the corners of thephotosensor array, though conveniently the optics for projecting andfocusing the image of information onto the photosensor array may beused. The marker beams bracket the optical field of view of thephotosensor array, desirably in alignment with the periphery thereof.Consequently any information, such as contained on bar code labels,within the region bounded by the marker beams is necessarily projectedor focused onto the photosensor array.

Once the image is focused on the photosensor array, the output of eachphotosensor element may be electrically read and stored in accordancewith data processing techniques. However, it needs to be pointed outthat the recorded or stored image is a "raw image", as it was receivedduring the instance of illumination. The image may contain an image ofdirt spots which may have adhered to portions of a bar code, forexample.

One advantage of the OCR device in accordance with the invention overtraditional scanner units is that an entire area of the code has beenrecorded or stored. A scanner typically operates to read a line orsection through a bar code, for example. A number of repeat readings maybe employed to achieve an average reading. However, with a more complexunit providing for such repeated scanning operations, any movementduring these repeat readings would tend to dilute the accuracy of any ofthe readinqs. Hence, in accordance with the invention, the imagerepresenting the entire information becomes fixed instantaneously withelectronics of the reader. Subsequently any number of readings may betaken and verified from the fixed or stored information. Also, any datamanipulation may be performed in accordance with known data processingtechniques to transform the stored image to a clearly recognizable datacode.

Another advantage is being realized with respect to recently developingtrends in the code marking art. With increasing understanding of dataprocessing techniques for inventory handling and merchandisingoperations in general, a need has emerged to pack more information intoeach single code combination or code cluster. Recent developmentssuggest replacing conventional single line bar codes with multi-line barcode patterns having a more densely packed configuration. Codes havingthese new configurations are generally known as "stacked bar codes."Simply stated, stacked bar codes are compressed in the directionperpendicular to the reading direction and are arranged in a multi-linestacked configuration, like a page of printed material. A number ofdiffering standards bar codes exist, two of which are known as "Code 49"and "16K". Code 49 may consist of stacked lines or rows of code indiciatwo to eight rows high, while the 16K code may use stacked rows of codeindicia between two and sixteen rows high.

It is understandable that with conventional code scanners, readingscanned codes at angles other than perfect alignment with the lineararrangement of the codes may present code recognition problems. Ofcourse, if less than the entire code information is recognized, theentire code is typically indicated as not having been read, so that are-read cycle must be initiated. Since valuable time may be lost byrepeating reading operations, it is of course desirable to recognize thecode. Since a code may also not have been recognized because of alateral shift of the active area of the scanner away from the labelconfiguration, either the angular misalignment or a lateral shift may bea cause for non-recognition of the code.

It is apparent that the current invention is particularly advantageousfor reading the described "stacked bar codes" as well as otherinformation. The referred to marker beams are able to indicate or showwhen the entire code pattern is within the region from which an image ofthe code pattern can be transferred to the photosensor array. Hence, amajor source of error is eliminated. Secondly, the instantaneousfocusing of the information on the photosensor array reduces the risk oferror caused by inadvertent movement of the reader during a prolongedprocess. Thirdly, since typical data processing techniques permit thecode to be aligned electronically after it has become stored in thereader, critical alignment requirements are no longer needed forinformation to be read from the stored code image.

Initial processing of the image is a normalization process whichsometimes also may be referred to as "calibration" during which theorientation of the image may be recognized and during which blemishes,such as dirt spots, may be recognized and image electronicallyreoriented and blemishes neutralized in accordance with known dataprocessing techniques. The stored image may then be read by the readerand the information may be transferred to desired electronic data banks.

In FIG. 45, an optical sensing area is delineated which represents theresult of the use of a typical solid state video imaging array with alens system that provides a magnification ratio of ten to one. Theresultant active area is 2.58 inches×1.94 inches as indicated.

FIG. 46 shows a diagrammatic view of an optical system that incorporatesthe components described. The ring flash is a preferred light source forits ability to provide relatively uniform illumination with minimumbackscatter into the imaging device. Also it may be "wrapped" around thelens, as shown, providing a compact, efficient package. The imagingarray may be placed directly in line with the optical axis of thereader, so that the optical portion of a hand-held reader can be quitecompact.

Operation of the reader consists of the user "aiming" at the targetlabel and activating a switch to initiate the read. The flashtube iseffective to provide an essentially instantaneous illumination, somovement of the hand-held reader during this time is noncritical. Thedigital processor immediately begins clocking the imaging array to readits contents which correspond to the intensity of the light from theactive sensing area that was focused on the imaging array. The actualoutput of the imaging array is normally an analog signal. Since onlywhite or dark information is needed, the conversion decision may consistof a comparator circuit with appropriately selected bandwidth andhysteresis to correspond to the characteristics of the imaging circuitoutput.

The digital information is assembled into sixteen bit data wordscorresponding to the word length of the digital processor and storeddirectly into the processor memory array. An entire image may consist of492 lines of 512 samples each for a total 251,904 bits or 31,488 bytesof information, as illustrated in FIG. 45. Once the image acquisitionprocess is complete, the digital processor may then begin operating onthe image information to remove blemish and noise components, rotate theimage to a normalized position, correct for optical skew due tocurvature of the target label or reading from an off-axis angle, and thelike, to optimize the pattern recognition process. An important featureof the described system is the ability of the digital processor todetect during such discussed normalization the locations of blemishes orflaws in the image sensing array and to store those locations in anon-volatile memory so that flawed image data may be masked orcompensated to remove such errors from consideration in the recognitionalgorithms.

When image normalization is complete, the recognition process may thenbegin. The first level of recognition is to determine whether the codedinformation is a bar code or a line of characters, for example. If a barcode is recognized, standard bar code decode algorithms may be employed.If a character format is recognized, then a character recognitionalgorithm is invoked.

The digital processor employed for the image normalization, processingand recognition functions must be extremely fast and efficient foracceptable user satisfaction. A processor such as the Texas InstrumentsTMS320C25 type which is designed for digital signal processingapplications has the ability to address external program and datamemory, perform bit and word manipulations and has extremely fastexecution speeds while operating with acceptable power consumptionlevels for a portable hand-held unit.

B. Specific Explanation of a Preferred Embodiment (Referring byReference Numerals to the Diagrammatic Illustrations of the Drawings).

Referring first generally to FIG. 46, there is illustrated somewhatschematically a hand-held area type optical reader. The reader, whichmay also be referred to as an improved Optical Character Reader ("OCR")device, represents an embodiment according to the present invention. Thereader, as will be explained is capable of reading all the characters,bar codes or other information at an optical sensing area such asindicated at Y10 in FIG. 45, essentially instantaneously. The area Y10to be read may be illuminated by light from a ring-type illuminator Y11, preferably a xenon flash tube. The reader shown schematically as ahand-held scanner unit Y12, indicated by dash lines, may house the lightsource Y11, and suitable optics, such as a lens Y14. The optics Y14include a focal plane at an interior region Y15 of the scanner unit orreader Y12. A solid state area type photosensor array such as indicatedat Y16 is disposed in the focal plane defined by the interior regionY15. The photosensor array Y16 is comprised of a plurality ofphotosensor elements arranged in an area corresponding in the sensingarea 10 externally of the reader Y12 to respective pixels, such as atY17, FIG. 45. The individual photosensor elements or pixels in the areaarray of photosensor elements or photosensor array 16 may have adensity, such as in typical video cameras. Thus, the sensing area 10, asan external projection of the photosensor array Y16, is enlarged withrespect to the photosensor array Y16 in accordance with a magnificationratio, such as ten to one, of optics of such video cameras. However,even with such enlargement of the sensing area Y10, the number of pixelsY17 illustrated in FIG. 45 provide a resolution of individual pixel of0.004 inch by 0.005 inch (four mils high by five mils wide).

Once the flash energization of the light source Y1 1 is complete, thephotosensor array Y16 may be read out, each line of photosensor elementsof the array being shifted out serially for example, and the respectivelines of photosensor elements being read out in parallel for example toan analog/logic interface component Y18 within the hand-held scannerunit Y12. A signal processor Y19, such as the referred to TexasInstruments TMS320C25 signal processor type, disposed in the scannerunit Y12 and connected with the analog/logic interface component Y18 mayreceive from the focussed information image e.g. at Y20; FIG. 46, thearea image data and supply the raw area image data to an associatedmemory Y21 in the hand-held scanner unit Y12 for subsequent processingin the hand-held unit. As an alternative, the raw area image data (e.g.in digital form) may be coupled via an RF or optical link Y22 to a hostprocessor (not indicated) for storage and processing. Such a separatehost processor may also be portable and carried by the user. Where thefocussed information image Y20, such as that of a bar code or stackedbar code as shown in FIGS. 48 through 50, on the photosensor array 16 istilted relative to the longitudinal (widthwise) axis of the array Y16,the raw image data as stored in digital form may be subsequentlyprocessed so as to be rotated into a normal horizontal disposition priorto decoding thereof by well known algorithms. In reference to FIG. 46,the flash tube Y11 and the lens Y14 may have circular symmetry relativeto their common longitudinal axis Y25 which is consequently also theoptical axis of the reader Y12. Hence the illuminator or flash tube Y1 1is disposed annularly about the optics represented by the lens Y14, sothat any angle of tilt of label Y30 about axis Y25 is not detrimental touniform optical imaging of the entire information field of the labelY30.

Marker beams Y31 originating from light sources Y36, Y37, Y38 and Y39 atthe four corners of area photosensor array Y16 may be projected onto asupporting surface Y40 carrying label Y30, via optics Y14, to producevisually discernible indicia, such as marker spots Y41, Y42, Y43 andY44, respectively, so that array 16 may be readily aligned relative toarea information e.g. on label Y30, as the hand-held unit Y12 is beingmoved into proximity thereto. By way of example, the light sourcesY36-Y39 may be light emitting diodes at the four corners of thephotosensor array Y16, which light emitting diodes may be sequentiallypulsed so that the marker spots Y41-Y44 are each produced at arepetition rate of sixty per second when the hand-held scanner unit isplaced in a target seeking mode. Once the four marker spots "bracket"the information to be read, as in FIGS. 46 and 49 through 51, regardlessof tilt, or regardless of whether the information extends horizontallyor vertically, the light source Y1 1 may be triggered, marker spotsY41-Y44 being extinguished by this time, or the wavelength thereof beingprevented from affecting the photosensor array by filtering, forexample.

As long as the marker spots Y41 through Y44 bracket the information tobe read, e.g., information on the label Y30, the image Y20 of the entireinformation field is necessarily focussed on the active orphotosensitive area of the photosensor array 16. It should be understoodthat only the information and not the entire label 30 needs to becomelocated within an area Y45 of the supporting surface Y40 bounded by themarker spots Y41 through Y44. FIG. 48 shows a stacked bar code label Y30disposed within the area Y45 bracketed by the marker spots Y41 throughY44. Hence the image of the information represented by the stacked barsof the label Y30 is projected onto and becomes focussed on the activearea of the photosensor array Y16. Though the information is capturedwithin the area Y45 at an angle, the image Y20 will still be focussed onthe photosensor array Y16. Hence the entire image Y20 with allinformation bearing dark and light configuration combinations of thecode can be read into memory locations of the memory Y21.

A first embodiment of manner in which the marker spots Y41 through Y44define the area Y45, such as described with respect to FIG. 46, is alsoillustrated in FIG. 48. The area Y45 as indicated by dashed lines isbracketed at its corners by the marker spots Y41 through Y44. Thus, toline up indicia to be read, such as the stacked bar code label Y30, anoperator would aim the marker spots Y41 through Y44 so that informationon the label does not extend to or beyond a straight line between twoadjacent ones of the marker spots. FIG. 49 illustrates an alternateembodiment of delineating the area Y45. In lieu of the marker spots Y41through Y44, FIG. 49 shows linear illumination bars Y46, Y47, Y48 andY49 which closely bound the area Y45, again as depicted again by thedashed lines. It may be preferred to mark the area Y45 by a linearillumination outline comprised of the illumination bars Y46 through Y49in that the photosensor array may be allowed to contain an uninterruptedmatrix without the need to preserve corner locations thereof for thelight emitting diode as described with respect to FIG. 48. Brieflyreferring back to FIG. 46, the illumination spots or bars Y46 throughY49 may be produced by light sources, such as light emitting diodes orlaser diodes in combination with linear lenses, which may be disposed inthe focal plane Y15 at midpoints of each of the edges of and is directlyadjacent the photosensor array Y16, as indicated by the numerals Y51,Y52, Y53 and Y54 respectively. Thus, as with respect to the earlierdescribed example, the optics Y14 may be used to direct light beamsresulting in the marker bars Y46 through Y49 through the optics Y14against the surface Y40.

FIG. 49 shows the label Y30 disposed at an increased angle with respectto the major outline of the area Y45 and of a smaller size. Again, thecriterion for focussing information on the active area of thephotosensor array Y16 is to aim the field of view of the reader Y12 asidentified to the user by the marker indicia such as the described spotsor bars so as to place the information to be read entirely within thearea Y45. If the angular alignment of the label Y30 is less than thatillustrated in FIG. 48, and is disposed at an angle with respect to theillustrated rectangular shape of the active field of view in FIG. 49,the user may simply back off the reader Y12 away from the surface Y40until the entire information area of the label Y30 is contained withinthe area Y45. An increased distance between the label Y30 and the readerY12 results in a smaller image of information being focussed on thephotosensor array Y16. However, as the label Y30 shown in FIG. 48, theentire label Y30 in FIG. 49 will become focused on the photosensor arrayY16. The flash illumination by the referred to xenon flash tube Y11 maybe chosen to allow the "f-stop" of the optics Y14 to be stopped downsuch that the depth of field of the reader is increased to allow theimage Y20 to become focused on the photosensor array Y16 even though thedistance between the reader Y12 and the supporting surface Y40 may varyfor example, between two inches to well in excess of one foot. It mayfurther be found convenient to use currently known and availableautomatic focusing techniques to further increase the ability of thereader to focus the image Y20 over a yet further increased range ofdistances of several feet between the indicia to be read and the readerY12. Such increase in versatility of the reader Y12 would result, ofcourse, in a corresponding increase in the cost of the reader.

FIG. 51 illustrates a light source (such as shown at Y51 through Y54 inFIG. 46), say source Y51, more generally identified as light sourceassembly Y55, in combination with a typical molded casing Y56 includinga lens Y57 for linearly expanding the light emitted from the source Y51in one or more directions away from its optical axis Y58. Thus, asillustrated in FIG. 49, the light emitted from the sources Y51 throughY54 is expanded linearly from center points shown at Y59 into twodirections disposed at a 180 degree angle. It may also be possible tochange the angle between the two legs Y61 and Y62 (FIG. 51) from 180degrees to for example a right angle between the two directions ofexpansion of the emitted light. With such modification, the expansiondirection Y62 would be directed into the plane or out of the plane ofthe drawing of FIG. 51. The configuration of marker spots Y61, Y62, Y63and Y64 in FIG. 50 illustrate a right angle expansion of the lightemitted through correspondingly configured lenses Y57. In theconfiguration of the marker spots Y61 through Y64 the correspondinglight sources would be located again at the corners of the photosensorarray Y16, as shown with respect to the light sources Y36 through Y39,for example. It would be expected that the intensity of the linearlydeflected or expanded light decreases with the distance from the opticalcenter of the non-deflected light beam. Thus, as shown in FIG. 49, thecorners of the area delineated by the marker bars Y46 through Y49 maynot be illuminated by the marker bars, while the centers of the sides ofthe area Y45 shown in FIG. 50 may not be illuminated or only slightlyilluminated relatively to more brightly illuminated corners by therespective marker spots Y61 through Y64. FIG. 50 also shows the label 30disposed entirely within the area Y45 delineated by the marker spots Y61through Y64. While FIGS. 48 through 50 show a somewhat rectangularconfiguration of the marker spots or bars, a square configuration with acorrespondingly square configuration of the photosensor array 16 may bepreferred. However, the particular shape of the photosensor array Y16and the marked or delineated area Y45 are not critical, as long as thearea 45 delineated by the marker spots defines the active area Y20disposed in the interior of the reader Y12.

In each of the different embodiments, a complete label, e.g. five incheshigh by five inches wide, having a complete bar code, or row or rows ofcharacters thereon, can be focussed onto the operative area of acomplete image photosensor array, such as Y16, in response to a singleessentially instantaneous flash of a light source, such as Y1 1. Asbecomes apparent, a relatively larger sized label Y30 would simplyrequire an operator of the reader to increase the distance between thelabel to be read and the reader Y12. In an advantageous embodiment, theheight dimension of the complete image area array Y16 may be such that acomplete area information image including the entire area informationwidth; e.g. of an-eighty column line of characters, can be read whetherthe width of the information image is disposed widthwise or heightwiseor diagonally on the photosensor array Y16. In general, such areainformation is focusable on the photosensor array Y16 in any angularorientation about the optical axis Y25. By way of example, a label Y30containing all its information in an area of square configuration 1.3inches on a side could be disposed so that its width extendedhorizontally or vertically or at an acute angle on the photosensor arrayY16 and in each case the entire contents of the label could be read witha single flash of-light source Y11.

Preferably the hand-held unit Y12 contains batteries "BATTERY"(schematically indicated in FIG. 46 at Y65) with sufficient energy so asto supply the flashable light source means Y11 and the other componentsof the hand-held unit, so that the unit is essentially self-containedand free of any connecting cable or the like.

The system of FIG. 46 may be provided with an autofocus ranging system,as already referred to above, so that the reader Y12 may have theability to read at extended distances, e.g., up to forty-eight inchesand possibly even greater distances, and may also be capable of readinga wider range of target areas. Autofocus systems are common in 35 mmcameras.

The hand-held scanner unit Y12 of FIG. 46 may contain the programming torecognize several types of optically discernible indicia of information,such as bar codes as well as conventional character fonts, and toautomatically select the appropriate decoding algorithm from thoseavailable in its on-board stored program. Furthermore, the hand-heldunit Y12 may contain an area array photosensor Y16 of size andresolution so as to register the above-mentioned multiple lines ofcharacters, e.g., eight lines of eighty characters each at one time.Preferably, the entire information field to be scanned, orinstantaneously to be recorded or read, such as represented by label Y30in FIG. 46 is illuminated simultaneously by a brief flash of highlyintense light source such as the xenon tube Y11.

The reading of bar codes with a complete area photosensor array such asY16, enables the digital data representing a bar code, for example, tobe rotated and otherwise normalized as a complete entity prior todecoding, such that the normalized data may correspond to that obtainedby sequentially scanning along a bar code parallel to the longitudinalbar code axis at a multiplicity of levels separated center to centere.g. by four mils. By combining the corresponding data points atdifferent levels, e.g., on an averaging basis, defects in the bar codeimage can be reliably overcome such as defects due to foreign matter,spurious marking and the like. Again, the bar code can be disposed atany random angle relative to the reader during the reading operation,speeding the reading of the labels, reducing operator fatigue andincreasing the number of labels which can be read during a working day.

FIG. 47 is a simplified functional block diagram showing the photosensorarray ("CCD") Y16 coupled through typical driver circuits ("BF") Y66 andY67 to the analog/logic interface ("A/L INTERFACE") Y18. The data signaloutput from such typical interface circuit Y18 would be coupled directlyto the above referred-to microprocessor circuit ("MICROPROCESSOR") Y19,such as the preferred Texas Instrument processor TMS320C25 type. A stateof the art signal processing circuit at the time of the priorapplication hereof, the circuit is still a preferred device, thoughother devices may be available and may be substituted therefor. Thespecifications of the device Y19 provide for 4K words of On-Chip ProgramROM and 544 Words of programmable On-Chip RAM.

Typically such minimum ROM (Read Only Memory) and RAM (Random AccessMemory) may be supplemented with further programmable memory, such asthe memory ("RAM") Y21, and with additional read only memory ("ROM")Y68. The processor circuit Y19 may address and transfer such additionalmemory by typical address and data buses Y69 and Y70, respectively. Datamay also be transferred to a suitable communication interface("COMM.INT.") Y71, which in turn is coupled to the above referred-tocommunication link Y22, which may be an RF or an optical link. It shouldbe understood that the specifically described elements and theirfunctions are merely for explanatory purposes and various changes may bepossible within the scope hereof.

FIG. 52 illustrates alternate embodiments of the present inventionindicative of changes within the broad scope of the invention. FIG. 52shows as FIG. 46 the supporting surface Y40 with the label Y30, such asa stacked bar code, for example, in relationship to the hand-heldoptical reader unit Y12. The reader unit Y12 also includes preferablytypical optics Y14 and a photosensor array Y16 disposed in a focal planeat an interior plane or region Y15 behind the optics Y14. An image Y20of information representative of the information on the label Y30 may beformed on the photosensor array Y16 when the reader Y12 is activated byinstantaneously illuminating an area ahead of the reader Y12 and hencethe supporting surface Y40 in the region of the label Y30 when thereader optical axis Y25 is aimed toward the label. The illuminator Y11which in the preferred embodiment is a flashable xenon tube, may ofcourse generally be of any of a number of flash type illuminators Y11.FIG. 52 therefore illustrates an annular illuminator Y11 which iscomprised of a number of discrete pulseable light emitting diodes Y76.The light emitting diodes are preferably disposed adjacent the exteriorportion of the optics Y14 of the reader Y12 in a plane perpendicular tothe optical axis 25, substantially similar to the arrangement of thexenon flash tube shown in FIG. 46. The number of discrete light emittingelements Y76 may be chosen to correspond to a total light intensityneeded to illuminate the exterior region of the label Y30. Depending onthe desired range over which the reader Y12 is to function, the numberof discrete devices may be increased by closer spaces between adjacentones of the light emitting diodes Y76.

FIG. 52 illustrates another change in the described embodiment withrespect to the previously described marker sources, such as the lightemitting diodes Y36 through Y39 or the light sources Y55 includinglenses Y57. Even though it is presently considered advantageous toproject beams from the marker sources through the optics Y14, withinreason it is possible to also project marker spots or bars, such as barsY77, Y78, Y79 or Y80 against the surface Y40 from respective markerlight sources Y81, Y82, Y83 and Y84 without having the projected beamsbe directed through the optics Y14 of the reader Y12. Thus, the markerlight sources Y81 through Y84 may be disposed externally of the opticsY14 and on a frontal portion Y85 of the reader Y12. The lenses Y57 ofthe light sources Y81 through Y84 may be disposed to direct therespective marker beams of the light sources substantially along theperiphery of the field of view of the optics 14 of the reader Y12. Asdescribed with respect to FIG. 51, the lenses Y57 may be shaped tolinearly shape the emitted light of the marker sources in two mutuallyopposite directions or at an angle other than 180 degrees, depending onthe location of the light sources. A disadvantage may possibly benoticed in that the marker sources are not in total alignment with theperiphery of the field of view of the optics Y14. Consequently, atextremes of an operating range of the reader Y12, resulting marker barsor spots, such as the marker bars 77 through 80 shown in FIG. 52 do notdelineate precisely the area 45 which corresponds precisely to theactive photosensor array Y16 projected against the surface Y40 throughthe optics Y14. However, only at close range, the marker spots or barsY77 through Y80 may form on the surface Y40 somewhat externally of theactual area Y45, hence indicating an area larger than one that may beread by the reader Y12. When the sources are properly placed suchdeviation may be confined to a range at which normally no readings aretaken. At a medium range, the marker bars may be disposed to clearlydelineate the area Y45. And an area smaller than the actual area Y45 maybe indicated at an extended distance for reading the label 30. Thus, forpractical purposes the marker sources may be oriented that forsubstantially all readings the predetermined area Y45 is bracketed. Itshould be understood that not only light sources for generating the barsY77 through Y80 may be disposed externally of the optics Y14, but lightsources disposed to project marker beams generally to corners of therectangular area Y45 may be disposed externally of the optics Y14. Suchalternate light sources Y86, Y87, Y88 and Y89 may similarly be disposedas closely as feasible adjacent the optics, and actually may be disposedwithin the annular configuration of flashable illuminator sourceelements Y76 as shown in FIG. 52. With respect to the latter sources,lenses Y57 may be disposed to linearly expand the respective markerbeams at right angles so as to bracket the area Y45 as indicated in FIG.50, for example. It should be understood that various other changessuggest themselves from the preferred embodiments as disclosed herein.

As an example of changes or variations in delineating the area Y45within the field of view of the reader Y12 the marker sources may beadvantageously limited in numbers. FIGS. 53 and 54 depict an example ofan alternate arrangement of marker sources, the respective impingingmarker spots being identified by numerals Y92 and Y93 in FIG. 53 and bynumerals Y94 and Y95 in FIG. 54. In each of the further describedembodiments, is marker sources are disposed to generate marker beamsimpinging on the surface 40 as the respective marker spots Y92, Y93, Y94and Y95 with the earlier described right angle expansion from diagonallyopposite corners Y96 and Y97 of the delineated area Y45 in FIG. 53, andfrom corners Y98 and Y99 of such area Y45 as shown in FIG. 54. Also, theorientation of the labels Y30 depict a substantially vertical orheightwise arrangement with respect to the area Y45 in FIG. 53, and asubstantially horizontal or widthwise arrangement of the label Y30 withrespect to the area Y45 in FIG. 54. The different orientations of therespective labels Y30 in each instance further illustrate the abovedescribed advantage of the reader in providing for the capture of anarea of information on the photosensor array independent of theorientation of such information about the optical axis of the reader.

With respect to the shape of the photosensor array Y16, photosensorarrays of the current state of the art are generally of rectangularshape or at least the active areas are of rectangular shape. While thepreferred embodiment discloses a generally circular lens or optics Y14,the shape thereof is preferred because of the generally rectangularshapes of so-called targets or photosensor arrays 16 of video cameras.It should be understood that the invention in its broad scope may notdepend on a sensing area of any particular shape.

The ability to capture and manipulate an entire image with a portableunit has important benefits for optical character reading also. In suchinstances a reading area of elongate rectangular shape may be preferred.For example, the described embodiments allow the use of imageenhancement algorithms, e.g., of the type developed for enhancement ofdeep space probe images, as well as image normalization, e.g., such asimage rotation and scaling. Non-linear scaling for improving recognitionefficiency with respect to irregular surfaces such as curved surfaces,and with respect to off-axis viewing angles, is also feasible.

IV. Description of FIG. 55

Optically readable information set reader Z10 may be constructed suchthat images of information sets Z14 may be focused onto an array Z16 viaan optical system Z12 and a plurality of mirrors M₁, M₂, and M₃. Eachmirror may reflect light of a different wavelength such that aninformation set is sequentially illuminated by light of varyingwavelengths. Since each illumination step will produce an image thereader Z10 may determine the readability of each image; reading onlythat image with the best focus and then notifying the operator. In thisway optically readable information sets Z14 may be read over asubstantial range of distance with a fixed optical string. It should beapparent that a single mirror may also be utilized such that by rotatingthe mirror so as to project images at various segments of the array Z16.

In an exemplary embodiment a chromatic lens system of the type describedin U.S. Ser. No. 07/945,174 filed Sep. 14, 1992 (issue fee paid) may beutilized as the lens system Z12. In this fashion an optically readableinformation set reader may be constructed to read information sets overa substantial range of distances.

Additionally, filters may be inserted into the optical string such thatthe different focal lengths of f₁, f₂, and f₃ may be efficientlyutilized for reading information sets over a substantial range ofdistance.

V. Description of FIG. 56

Enhanced exposure control may be achieved by averaging the reflectedlight from an optical information set during a reading operation andthen terminating integration of the reflected light from an opticalinformation set after an optimum measurement sample of the reflectedlight image has been received. For example, this may be achieved byutilizing a charge coupled device (CCD) or the like with an electronicshutter with a PIN photodiode. A voltage is output when the device isexposed to light. The PIN photodiode charges capacitor C₁ through R₁.Resistors R₂ and R₃ set a threshold value for the comparator K₁. Oncethe charge on C1 exceeds the threshold, the comparator changes states.The R₄, C₂ pair controls timing of the base drive to the transistor T₁.The latch and/or one shot (monstable multivibrator) condition the outputof the circuit and adjust signal compatibility to the CCD. The outputsignal terminates further exposure during integration time (FIG. 56).

The transistor T₁ flushes accumulated charge on C₁. Since the comparatorchanges states when this happens, the resistor/capacitor pair (R₄, C₂)maintain enough base drive to fully flush the capacitor. The latch orone shot circuit makes the output signal durable enough to be insynchronization with the CCD exposure cycle.

More than one PIN photodiode may be used to increase the output voltage.Since the capacitor voltage at the end of the discharge phase willapproximate V_(ce) for the transistor, the reference voltage may beconsidered to retain this value. A high resistance "bleed resistor" mayalso be utilized with the transistor so as to force the capacitorinitial voltage to be very nearly ground.

It will be apparent that many modifications and variations may beeffected without departing from the teachings and concepts of thepresent disclosure.

What Is claimed Is:
 1. A hand-held indicia reader, comprising;A) anindicia sensor; B) a distance measurement component; and C) a readeradjustment system; wherein said reader adjustment system configures thereader to read indicia at the distance determined by said distancemeasurement component.
 2. The hand-held indicia reader according toclaim 1, further comprising a keyboard.
 3. A hand-held imaging deviceoperable over a range of distances, comprising:a) an image capturesystem capable of capturing and digitizing an image; b) a first distancedeterminer determining distance from the hand-held imaging device to anitem to be imaged; and c) an adjuster system; wherein said adjustersystem automatically adapts the hand-held imaging device to capture animage based on determined distance.
 4. The hand-held imaging deviceaccording to claim 3, wherein said adjuster system adjusts a lens systemof the hand-held indicia imaging device based on distance determined bysaid first distance determiner.
 5. A method of capturing an imagelocated at a distance from a hand-held imaging device, the hand-heldimaging device comprising a distance determiner, said method comprisingthe steps of:a) determining distance between the hand-held imagingdevice and an image to be captured; and b) automatically configuring thehand-held imaging device to capture an image located at the determineddistance.
 6. The hand-held imaging device according to claim 3, furthercomprising a user interface.
 7. The hand-held imaging device accordingto claim 3, wherein the hand-held imaging device comprises a seconddistance determiner.
 8. The hand-held imaging device according to claim3, further comprising an actuator.
 9. The hand-held imaging deviceaccording to claim 3, wherein said image capture system comprises acharge coupled device.
 10. The hand-held imaging device according toclaim 3, wherein said first distance determiner comprises an ultrasonictransducer.
 11. The hand-held imaging device according to claim 3,wherein said first distance determiner comprises an infrared distancedeterminer.
 12. The hand-held imaging device according to claim 3,wherein said adjuster system comprises an adjustment motor.
 13. Thehand-held imaging device according to claim 3, further comprising anaudible status indicator.
 14. The hand-held imaging device according toclaim 3, further comprising a visual status indicator.
 15. The hand-heldimaging device according to claim 3, further comprising a statusindicator indicating whether an image to be captured is outside thehand-held imaging device's operative range.
 16. The hand-held imagingdevice according to claim 3, wherein said adjuster system is disabledwhen an image to be captured is determined to be outside the hand-heldimaging device's operative range.
 17. The hand-held imaging deviceaccording to claim 3, further comprising an indicia decoder component.18. The hand-held imaging device according to claim 3, furthercomprising a display providing information on image capture operations.19. The hand-held imaging device according to claim 3, furthercomprising a field of view marking system.
 20. The hand-held imagingdevice according to claim 19, wherein said field of view marking systemdirects visible light to indicate a boundary of the field of view. 21.The hand-held imaging device according to claim 3, wherein said adjustersystem adapts the hand-held imaging device to read at various distanceswithout manipulating movable components.
 22. The hand-held imagingdevice according to claim 21, wherein said adjuster system comprisesmultiple optical image paths.
 23. The hand-held imaging device accordingto claim 3, wherein said image capture system comprises a photosensitivearray.
 24. The hand-held imaging device according to claim 23, furthercomprising an intensity sensor.
 25. The hand-held imaging deviceaccording to claim 3, further comprising a communication component. 26.The hand-held imaging device according to claim 25, wherein saidcommunication component comprises a radio frequency transceiver.
 27. Thehand-held imaging device according to claim 25, wherein the hand-heldimaging device communicates with a remotely located device via saidcommunication component.
 28. The hand-held imaging device according toclaim 3, further comprising an electromagnetic energy generatordirecting electromagnetic energy toward an image to be captured.
 29. Thehand-held imaging device according to claim 28, wherein the hand-heldimaging device comprises more than one electromagnetic generator. 30.The hand-held imaging device according to claim 29, wherein saidelectromagnetic energy generator comprises a light energy generator. 31.The hand-held imaging device according to claim 30, wherein said lightenergy generator comprises a flashable illuminator.
 32. The methodaccording to claim 5, wherein the step of automatically configuring isnot performed if the determined distance is not within the hand-heldimaging device's operation range.
 33. The method according to claim 5,wherein the hand-held imaging device comprises an image capture systemcapable of digitizing a captured image.
 34. The method according toclaim 5, further comprising the step of aiming the hand-held imagingdevice toward an image to be captured prior to the step of determiningdistance.
 35. The method according to claim 34, further comprising thestep of activating an aiming aid prior to the step of aiming.
 36. Themethod according to claim 35, wherein said aiming aid also providesfield of view information.
 37. The method according to claim 5, furthercomprising the step of directing electromagnetic energy toward an imageto be captured after the step of automatically configuring.
 38. Themethod according to claim 37, wherein light is directed toward an imageto be captured.
 39. The method according to claim 37, further comprisingthe step of automatically terminating the step of directingelectromagnetic energy toward an image to be captured after determiningthat a sufficient representation of the image has been captured.
 40. Themethod according to claim 5, further comprising the step of capturingand digitizing a first image located at the determined distance afterthe step of automatically configuring.
 41. The method according to claim40, further comprising the step of automatically terminating thecapturing step after determining that a sufficient representation hasbeen obtained.
 42. The method according to claim 40, further comprisingthe step of indicating a successful image capture to a user after thestep of capturing.
 43. The method according to claim 40, furthercomprising the step of indicating an unsuccessful image capture to auser after the step of capturing.
 44. The method according to claim 40,further comprising the step of automatically reinitiating the method ofcapturing an image.
 45. The method according to claim 40, furthercomprising the step of transmitting a captured image to a remote device.46. The method according to claim 45, wherein the step of transmittingis accomplished by radio frequency transmission.
 47. The methodaccording to claim 40, further comprising the step of decoding acaptured image after the step of capturing.
 48. The method according toclaim 47, further comprising the step of transmitting a decoded capturedimage to a remote device after the step of decoding.
 49. The methodaccording to claim 48, wherein the step of transmitting is accomplishedby radio frequency transmission.
 50. The method according to claim 40,further comprising the step of automatically capturing a second imageafter said step of capturing.
 51. The method according to claim 50,wherein said step of automatically capturing automatically captures adifferent area than was captured for the first image.
 52. The methodaccording to claim 50, wherein said step of automatically capturing isaccompanied by an automatic illumination of the second image to becaptured.
 53. The method according to claim 40, further comprising thestep of automatically successively capturing a plurality of images aftersaid step of capturing.
 54. The method according to claim 50, furthercomprising the step of automatically successively illuminating, at timeof capture, each image to be captured.
 55. The method according to claim53, wherein said step of automatically successively capturing ismanually initiated by an operator of the hand-held imaging device.